scsi: ufs: ufshcd: Remove VLA usage

scsi: ufs: ufshcd: Remove VLA usage

On the quest to remove all VLAs from the kernel[1] this moves buffers
off the stack. In the second instance, this collapses two separately
allocated buffers into a single buffer, since they are used
consecutively, which saves 256 bytes (QUERY_DESC_MAX_SIZE + 1) of stack
space.

[1] https://lkml.kernel.org/r/CA+55aFzCG-zNmZwX4A2FQpadafLfEzK6CC=qPXydAacU1RqZWA@mail.gmail.com

Signed-off-by: Kees Cook <keescook@chromium.org>
Reviewed-by: Subhash Jadavani <subhashj@codeaurora.org>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>