ION: Clean Up separate ION

ION_MSM and MSM_ION are redundant, so we'll use ION_MSM

Switch to ION_COMMON to stay uniform with naming

Define ION configs in the separate folders: ION-MSM and ION-Common respectively

Remove references to the drivers/gpu/Kconfig that we no longer need

Change-Id: I209c9e4b82e62a6b10761ff7e2bc8e259de6dcff
defconfigs: Update defconfigs with make defconfig, cleanup ION

Change-Id: I471411a5e8974356f9c7c05e3d539a150a7e776b