fsl/errata: move fsl_errata.h to common directory

move arch/powerpc/include/asm/fsl_errata.h to include/fsl_errata.h
to make it public for both ARM and POWER SoCs.

Signed-off-by: Shengzhou Liu <Shengzhou.Liu@freescale.com>
[York Sun: fix soc.h path in fsl_errata.h]
Reviewed-by: York Sun <yorksun@freescale.com>