powerpc/b4860: Adding workaround errata A-005871

Per the latest errata updated, B4860/B4420 Rev 1.0 has also
errata A-005871, so adding define A-005871 for B4 SoCs.

Signed-off-by: Shengzhou Liu <Shengzhou.Liu@freescale.com>
Signed-off-by: Andy Fleming <afleming@freescale.com>
1 file changed