powerpc: introduce and document sdhci,wp-inverted property for eSDHC

eSDHC block in MPC837x SOCs reports inverted write-protect state, soon
sdhci-of driver will look for sdhci,wp-inverted properties to decide
whether apply a specific quirk.

So, document the property and add it to device tree source files.

Signed-off-by: Anton Vorontsov <[e-mail]>
Cc: Pierre Ossman <[e-mail]>
Cc: Kumar Gala <[e-mail]>
Cc: David Vrabel <[e-mail]>
Cc: Ben Dooks <[e-mail]>
Cc: Sascha Hauer <[e-mail]>
Cc: Benjamin Herrenschmidt <[e-mail]>
Cc: <[e-mail]>
Signed-off-by: Andrew Morton <[e-mail]>
Signed-off-by: Linus Torvalds <[e-mail]>

Documentation/powerpc/dts-bindings/fsl/esdhc.txt

···
   - interrupts : should contain eSDHC interrupt.
   - interrupt-parent : interrupt source phandle.
   - clock-frequency : specifies eSDHC base clock frequency.
+  - sdhci,wp-inverted : (optional) specifies that eSDHC controller
+    reports inverted write-protect state;
   - sdhci,1-bit-only : (optional) specifies that a controller can
     only handle 1-bit data transfers.
 

arch/powerpc/boot/dts/mpc8377_mds.dts

···
 				reg = <0x2e000 0x1000>;
 				interrupts = <42 0x8>;
 				interrupt-parent = <&ipic>;
+				sdhci,wp-inverted;
 				/* Filled in by U-Boot */
 				clock-frequency = <0>;
 			};

arch/powerpc/boot/dts/mpc8377_rdb.dts

···
 				reg = <0x2e000 0x1000>;
 				interrupts = <42 0x8>;
 				interrupt-parent = <&ipic>;
+				sdhci,wp-inverted;
 				/* Filled in by U-Boot */
 				clock-frequency = <111111111>;
 			};

arch/powerpc/boot/dts/mpc8377_wlan.dts

···
 				reg = <0x2e000 0x1000>;
 				interrupts = <42 0x8>;
 				interrupt-parent = <&ipic>;
+				sdhci,wp-inverted;
 				clock-frequency = <133333333>;
 			};
 		};

arch/powerpc/boot/dts/mpc8378_mds.dts

···
 				reg = <0x2e000 0x1000>;
 				interrupts = <42 0x8>;
 				interrupt-parent = <&ipic>;
+				sdhci,wp-inverted;
 				/* Filled in by U-Boot */
 				clock-frequency = <0>;
 			};

arch/powerpc/boot/dts/mpc8378_rdb.dts

···
 				reg = <0x2e000 0x1000>;
 				interrupts = <42 0x8>;
 				interrupt-parent = <&ipic>;
+				sdhci,wp-inverted;
 				/* Filled in by U-Boot */
 				clock-frequency = <111111111>;
 			};

arch/powerpc/boot/dts/mpc8379_mds.dts

···
 				reg = <0x2e000 0x1000>;
 				interrupts = <42 0x8>;
 				interrupt-parent = <&ipic>;
+				sdhci,wp-inverted;
 				/* Filled in by U-Boot */
 				clock-frequency = <0>;
 			};

arch/powerpc/boot/dts/mpc8379_rdb.dts

···
 				reg = <0x2e000 0x1000>;
 				interrupts = <42 0x8>;
 				interrupt-parent = <&ipic>;
+				sdhci,wp-inverted;
 				/* Filled in by U-Boot */
 				clock-frequency = <111111111>;
 			};