target-i386/cpu: Add new EPYC CPU model

target-i386/cpu: Add new EPYC CPU model

Add a new base CPU model called 'EPYC' to model processors from AMD EPYC
family (which includes EPYC 76xx,75xx,74xx, 73xx and 72xx).

The following features bits have been added/removed compare to Opteron_G5

Added: monitor, movbe, rdrand, mmxext, ffxsr, rdtscp, cr8legacy, osvw,
       fsgsbase, bmi1, avx2, smep, bmi2, rdseed, adx, smap, clfshopt, sha
       xsaveopt, xsavec, xgetbv1, arat

Removed: xop, fma4, tbm

Cc: Paolo Bonzini <[email protected]>
Cc: Richard Henderson <[email protected]>
Cc: Eduardo Habkost <[email protected]>
Cc: Tom Lendacky <[email protected]>
Signed-off-by: Brijesh Singh <[email protected]>
Message-Id: <20170815170051[email protected]>
Reviewed-by: Eduardo Habkost <[email protected]>
Signed-off-by: Eduardo Habkost <[email protected]>