x86: consolidate xchg and xadd macros
x86: consolidate xchg and xadd macros

They both have a basic "put new value in location, return old value"
pattern, so they can use the same macro easily.

Signed-off-by: Jeremy Fitzhardinge <b3f594e10a9edcf5413cf1190121d45078c62290@goop.org>

TeamVee-Kanas/android_kernel_samsung_kanas,KristFoundation/Programs,KristFoundation/Programs,TeamVee-Kanas/android_kernel_samsung_kanas,KristFoundation/Programs,KristFoundation/Programs,TeamVee-Kanas/android_kernel_samsung_kanas,TeamVee-Kanas/android_kernel_samsung_kanas,TeamVee-Kanas/android_kernel_samsung_kanas,KristFoundation/Programs,KristFoundation/Programs