[SCSI] qla2xxx: Wait for FLASH write-protection to complete after a write.

Some flash parts have a slow enable write-protection (WP)
operation whereby subsequent FLASH accesses would fail if the WP
operation had not completed.  Software now polls the SPI's
status-register for WP completion.

Signed-off-by: Andrew Vasquez <andrew.vasquez@qlogic.com>
Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com>