ARM: Instruction set features clean-up.

Clean-up the instruction set features for ARM. Remove all the CPU variants
that are not supported or used with ART.

Remove:
 - Old cpu variants (eg: arm7tdmi - does not have the features needed by ART).
 - M & R class cpu variants (currently ART only runs on A class cpus).
 - cpu variants that are unlikely to be used with ART  (eg: cyclone).

Test: mma test-art-target && mma test-art-host

Change-Id: I2b7e5169022ea0a5a943281381b9446c52e17364