LU-18225 kernel: silent page allocation failure in virtio_scsi

LU-18225 kernel: silent page allocation failure in virtio_scsi

virtio_scsi uses GFP_ATOMIC to allocate memory, with large
requests sometimes the allocation fails.
We don't need to throw up the allocation error and dump stack
for this as virtio_scsi will return SCSI_MLQUEUE_HOST_BUSY
which translates to BLK_STS_RESOURCE and that will be
handled by upper layers.

Change-Id: I7117711d05794d57ab294f3bc6746de1979afc22
Test-Parameters: trivial
Signed-off-by: Li Dongyang <dongyangli@ddn.com>
Reviewed-on: https://review.whamcloud.com/c/fs/lustre-release/+/56644
Tested-by: jenkins <devops@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: Andreas Dilger <adilger@whamcloud.com>
Reviewed-by: Ronnie Sahlberg <rsahlberg@whamcloud.com>
Reviewed-by: Oleg Drokin <green@whamcloud.com>