scsi: megaraid: Remove redundant assignment to variable 'retval'

scsi: megaraid: Remove redundant assignment to variable 'retval'

The variable 'retval' is being assigned a value that is not being read
afterwards. The assignment is redundant and can be removed.

Cleans up clang scan warning:

Although the value stored to 'retval' is used in the enclosing
expression, the value is never actually read from 'retval'
[deadcode.DeadStores]

Signed-off-by: Colin Ian King <colin.i.king@gmail.com>
Link: https://lore.kernel.org/r/20240118121441.2533620-1-colin.i.king@gmail.com
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>