mseal: remove can_do_mseal()

No code logic change.

can_do_mseal() is called exclusively by mseal.c, and mseal.c is compiled
only when CONFIG_64BIT flag is set in makefile.  Therefore, it is
unnecessary to have 32 bit stub function in the header file, remove this
function and merge the logic into do_mseal().

Link: https://lkml.kernel.org/r/20241206013934.2782793-1-jeffxu@google.com
Link: https://lkml.kernel.org/r/20241206194839.3030596-2-jeffxu@google.com


Signed-off-by: Jeff Xu <jeffxu@chromium.org>
Reviewed-by: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Cc: Jorge Lucangeli Obes <jorgelo@chromium.org>
Cc: Kees Cook <keescook@chromium.org>
Cc: Liam R. Howlett <Liam.Howlett@Oracle.com>
Cc: Pedro Falcato <pedro.falcato@gmail.com>
Cc: Randy Dunlap <rdunlap@infradead.org>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>