ksmbd: replace sessions list in connection with xarray

[ Upstream commit e4d3e6b5 ]

Replace sessions list in connection with xarray.

Signed-off-by: Namjae Jeon <linkinjeon@kernel.org>
Reviewed-by: Hyunchul Lee <hyc.lee@gmail.com>
Signed-off-by: Steve French <stfrench@microsoft.com>
Stable-dep-of: 7b432337 ("ksmbd: fix deadlock in ksmbd_find_crypto_ctx()")
Signed-off-by: Sasha Levin <sashal@kernel.org>