arch: drop ALIGN_STR

arch: drop ALIGN_STR

... as being unused and having been unusable: It was clearly intended
for use in asm(), yet was placed inside __ASSEMBLY__ conditionals.

Also drop __ALIGN{,_STR} - there's no need to have a second flavor of
these constructs with no difference in behavior.

Signed-off-by: Jan Beulich <jbeulich@suse.com>
Reviewed-by: Andrew Cooper <andrew.cooper3@citrix.com>
Reviewed-by: Julien Grall <julien.grall@arm.com>