msm8960-common: remove unused (and incorrect) flag

* TARGET_ARCH_VARIANT_CPU is only used for armv6
* TARGET_USE_KRAIT_BIONIC_OPTIMIZATION is deprecated

Change-Id: I1958199076b4e7b5be37f77260c819d814de9c69
Merge pull request #1 from CyanogenMod/cm-11.0

msm8960-common: remove unused (and incorrect) flag