nfsd: more robust allocation failure handling in nfsd_file_cache_init

nfsd: more robust allocation failure handling in nfsd_file_cache_init

The nfsd file cache table can be pretty large and its allocation
may require as many as 80 contigious pages.

Employ the same fix that was employed for similar issue that was
reported for the reply cache hash table allocation several years ago
by commit 420f385531bb ("nfsd: more robust allocation failure handling
in nfsd_reply_cache_init").

Fixes: a773ac40fe37 ("nfsd: add a new struct file caching facility to nfsd")
Link: https://lore.kernel.org/linux-nfs/e3cdaeec85a6cfec980e87fc294327c0381c1778.camel@kernel.org/
Suggested-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Tested-by: Amir Goldstein <amir73il@gmail.com>