mwifiex: Use pci_release_region() instead of a pci_release_regions()

PCI regions are associated with the device using
pci_request_region() call. Hence use pci_release_region()
instead of pci_release_regions().

Cc: <stable@vger.kernel.org> # 3.2+
Signed-off-by: Yogesh Ashok Powar <yogeshp@marvell.com>
Signed-off-by: Amitkumar Karwar <akarwar@marvell.com>
Signed-off-by: Avinash Patil <patila@marvell.com>
Signed-off-by: Bing Zhao <bzhao@marvell.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>