filelock: __fcntl_getlease: fix kernel-doc warnings

filelock: __fcntl_getlease: fix kernel-doc warnings

Use the correct function name and add description for the @flavor
parameter to avoid these kernel-doc warnings:

Warning: fs/locks.c:1706 function parameter 'flavor' not described in
 '__fcntl_getlease'
WARNING: fs/locks.c:1706 expecting prototype for fcntl_getlease().
 Prototype was for __fcntl_getlease() instead

Fixes: 1602bad16d7d ("vfs: expose delegation support to userland")
Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
Link: https://patch.msgid.link/20251128000826.457120-1-rdunlap@infradead.org
Signed-off-by: Christian Brauner <brauner@kernel.org>