powerpc/mpc85xx: modify erratum A007186

T2080 v1.0 has this errata while v1.1 has fixed
this errata by hardware, add a new function has_errata_a007186
to check the SVR_SOC_VER, SVR_MAJ and SVR_MIN first,
if the sil has errata a007186, then run the errata code,
if not, doesn't run the code.

Signed-off-by: Zhao Qiang <B45475@freescale.com>
Reviewed-by: York Sun <yorksun@freescale.com>