scsi: storvsc: Fix storvsc_queuecommand() memory leak

Fix possible memory leak in error path of storvsc_queuecommand() when
DMA mapping fails.

Signed-off-by: Juan Vazquez <juvazq@linux.microsoft.com>
Reviewed-by: Tianyu Lan <Tianyu.Lan@microsoft.com>
Link: https://lore.kernel.org/r/20220109001758.6401-1-juvazq@linux.microsoft.com
Signed-off-by: Wei Liu <wei.liu@kernel.org>