scsi: arcmsr: clean up clang warning on extraneous parentheses

There are extraneous parantheses that are causing clang to produce a
warning so remove these.

Clean up 3 clang warnings:
equality comparison with extraneous parentheses [-Wparentheses-equality]

Signed-off-by: Colin Ian King <colin.king@canonical.com>
Acked-by: Ching Huang <ching2048@areca.com.tw>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>