pcmcia: add error handling for pcmcia_enable_device in qlogic_stub

When pcmcia_enable_device fails, the lack of error-handling code may
cause unexpected results.

This patch adds error-handling code after calling pcmcia_enable_device
in the qlogic_stub scsi driver.

Signed-off-by: Zhouyang Jia <jiazhouyang09@gmail.com>
Cc: James E.J. Bottomley <jejb@linux.vnet.ibm.com>
Cc: Martin K. Petersen <martin.petersen@oracle.com>
Cc: linux-scsi@vger.kernel.org
[linux@dominikbrodowski.net: update commit message]
Signed-off-by: Dominik Brodowski <linux@dominikbrodowski.net>