EDAC, mpc85xx: Silence unused variable warning

We were getting this build warning:

drivers/edac/mpc85xx_edac.c:1247:6: warning: unused variable 'pvr'

pvr is only used if CONFIG_FSL_SOC_BOOKE is defined. Declare it
__maybe_unused.

Suggested-by: Guenter Roeck <[e-mail]>
Signed-off-by: Sudip Mukherjee <[e-mail]>
Reviewed-by: Johannes Thumshirn <[e-mail]>
Cc: linux-edac <[e-mail]>
Link: http://lkml.kernel.org/r/[e-mail]
Signed-off-by: Borislav Petkov <[e-mail]>

drivers/edac/mpc85xx_edac.c

···
 static int __init mpc85xx_mc_init(void)
 {
 	int res = 0;
-	u32 pvr = 0;
+	u32 __maybe_unused pvr = 0;
 
 	printk(KERN_INFO "Freescale(R) MPC85xx EDAC driver, "
 	       "(C) 2006 Montavista Software\n");