M2: msm: simplify ifdefs (no functional change)

I made these before we had a unified "MACH_M2" (thanks invisiblek).
Looks better now.

Change-Id: Ibfd7e22267acb13eea7fc1778994affccbec196d
Merge tag 'AU_LINUX_ANDROID_JB_2.5.04.02.02.40.236' of git://codeaurora.org/kernel/msm into cm-10.1

AU_LINUX_ANDROID_JB_2.5.04.02.02.40.236 based on quic/aosp/jb_2.5