While allocating firmware dump, check if dump is already collected and do
not re-allocate the buffer.

Link: https://lore.kernel.org/r/20220110050218.3958-17-njavali@marvell.com
Cc: stable@vger.kernel.org
Signed-off-by: Joe Carnuccio <joe.carnuccio@cavium.com>
Signed-off-by: Nilesh Javali <njavali@marvell.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>