VIDEO: amba clcd: don't disable an already disabled clock

Fix the clock enable/disable tracking in the AMBA CLCD driver so
that the driver doesn't try to disable an already disabled clock,
thereby causing the clock (if shared) to become unbalanced.

This resolves a problem with CLCD on LPC32xx ARM platforms.

Reported-by: Kevin Wells <[e-mail]>
Signed-off-by: Russell King <[e-mail]>

drivers/video/amba-clcd.c

···
 	/*
 	 * Disable CLCD clock source.
 	 */
-	clk_disable(fb->clk);
+	if (fb->clk_enabled) {
+		fb->clk_enabled = false;
+		clk_disable(fb->clk);
+	}
 }
 
 static void clcdfb_enable(struct clcd_fb *fb, u32 cntl)
···
 	/*
 	 * Enable the CLCD clock source.
 	 */
-	clk_enable(fb->clk);
+	if (!fb->clk_enabled) {
+		fb->clk_enabled = true;
+		clk_enable(fb->clk);
+	}
 
 	/*
 	 * Bring up by first enabling..

include/linux/amba/clcd.h

···
 	u16			off_cntl;
 	u32			clcd_cntl;
 	u32			cmap[16];
+	bool			clk_enabled;
 };
 
 static inline void clcdfb_decode(struct clcd_fb *fb, struct clcd_regs *regs)