module: Fix prefix for module.sig_enforce module param

Commit cfc1d277 ("module: Move all into module/") changed the prefix
of the module param by moving/renaming files.  A later commit also moves
the module_param() into a different file, thereby changing the prefix
yet again.

This would break kernel cmdline compatibility and also userspace
compatibility at /sys/module/module/parameters/sig_enforce.

So, set the prefix back to "module.".

Fixes: cfc1d277

 ("module: Move all into module/")
Link: https://lore.kernel.org/lkml/20220602034111.4163292-1-saravanak@google.com/
Cc: Christophe Leroy <christophe.leroy@csgroup.eu>
Cc: Aaron Tomlin <atomlin@redhat.com>
Acked-by: Luis Chamberlain <mcgrof@kernel.org>
Signed-off-by: Saravana Kannan <saravanak@google.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>