lsm: fix a missing security_uring_allowed() prototype

lsm: fix a missing security_uring_allowed() prototype

The !CONFIG_SECURITY dummy function was declared as an "extern int"
instead of "static inline" (likely a copy-n-paste error), which was
was causing the compiler to complain about a missing prototype.  This
patch converts the dummy definition over to a "static inline" to resolve
the compiler problems.

Reported-by: kernel test robot <lkp@intel.com>
Reported-by: Stephen Rothwell <sfr@canb.auug.org.au>
Closes: https://lore.kernel.org/oe-kbuild-all/202502081912.TeokpAAe-lkp@intel.com/
Fixes: c6ad9fdbd44b ("io_uring,lsm,selinux: add LSM hooks for io_uring_setup()")
Signed-off-by: Paul Moore <paul@paul-moore.com>