powerpc/44x: Fix mask and shift to zero bug

My static checker complains that 0x00001800 >> 13 is zero. Looking at
the context, it seems like a copy and paste bug from the line below
and probably 0x3 << 13 or 0x00006000 was intended.

Fixes: 2af59f7d5c3e ("[POWERPC] 4xx: Add 405GPr and 405EP support in boot wrapper")
Signed-off-by: Dan Carpenter <[e-mail]>
Acked-by: Benjamin Herrenschmidt <[e-mail]>
Signed-off-by: Michael Ellerman <[e-mail]>

arch/powerpc/boot/4xx.c

···
 		fbdv = 16;
 	cbdv = ((pllmr & 0x00060000) >> 17) + 1; /* CPU:PLB */
 	opdv = ((pllmr & 0x00018000) >> 15) + 1; /* PLB:OPB */
-	ppdv = ((pllmr & 0x00001800) >> 13) + 1; /* PLB:PCI */
+	ppdv = ((pllmr & 0x00006000) >> 13) + 1; /* PLB:PCI */
 	epdv = ((pllmr & 0x00001800) >> 11) + 2; /* PLB:EBC */
 	udiv = ((cpc0_cr0 & 0x3e) >> 1) + 1;