libpixelflinger: conform ASM to UAL

Summary:
To use clang's integrated as, ASM is required
to conform to the UAL standards (Unified Assembler Language).
This does not negatively affect building with an external assembler.

This commit includes the following changes:

  - The binutils assembler assumes .align 2 if .align
    only is set, however the integrated as doesn't make this assumption.

  - .macro should not have ',' after the identifier, since the assumption
    is made that it's an additional (unrecognized) directive.

  - Use the more acceptable and supported ldmfd over ldmlofd

Test Plan: verified

Reviewers: randall.rushing, jriordan001, anders3408, synergy

Reviewed By: synergy

Differential Revision: http://review.codefirex.com/D176