apparmor: Fix match_mnt_path_str() and match_mnt() kernel-doc comment

Fix a spelling problem and change @mntpath to @path to remove warnings
found by running scripts/kernel-doc, which is caused by using 'make W=1'.

security/apparmor/mount.c:321: warning: Function parameter or member
'devname' not described in 'match_mnt_path_str'
security/apparmor/mount.c:321: warning: Excess function parameter
'devnme' description in 'match_mnt_path_str'
security/apparmor/mount.c:377: warning: Function parameter or member
'path' not described in 'match_mnt'
security/apparmor/mount.c:377: warning: Excess function parameter
'mntpath' description in 'match_mnt'

Reported-by: Abaci Robot <abaci@linux.alibaba.com>
Signed-off-by: Yang Li <yang.lee@linux.alibaba.com>
Signed-off-by: John Johansen <john.johansen@canonical.com>