Revert "arm64: alternatives: add enable parameter to conditional asm macros"

Commit 77ee306c ("arm64: alternatives: add enable parameter to
conditional asm macros") extended the alternative assembly macros.
Unfortunately this does not really work as one would expect, as the
enable parameter in fact correctly protects the alternative section
magic, but not the actual code sequences.
This results in having both the original instruction(s) _and_  the
alternative ones, if enable if false.
Since there is no user of this macros anyway, just revert it.

This reverts commit 77ee306c

.

Signed-off-by: Andre Przywara <andre.przywara@arm.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>