arm: Allow overriding the alignment set in the function macro

The function macro always sets .align 2 before declaring the
function label (since 5c5e1ea3) and always sets the section to
.text (since 278caa6a).

The .align 5 before certain functions, added in fc252eba, were added
before .text and .align were added to the function macro and thus
became useless/unused when the function macro got them.

This restores the original intention, to align the loop entry
points.

Signed-off-by: Martin Storsjö <martin@martin.st>
