mtip32xx: Use pci_enable_msi() instead of pci_enable_msi_range()

Commit "mtip32xx: Use pci_enable_msix_range() instead of
pci_enable_msix()" was unnecessary, since pci_enable_msi()
function is not deprecated and is still preferable for
enabling the single MSI mode. This update reverts usage of
pci_enable_msi() function.

Besides, the changelog for that commit was bogus, since
mtip32xx driver uses MSI interrupt, not MSI-X.

Cc: Jens Axboe <axboe@kernel.dk>
Cc: Asai Thambi S P <asamymuthupa@micron.com>
Cc: linux-pci@vger.kernel.org

Signed-off-by: Jens Axboe <axboe@fb.com>