PCI/MSI: Remove duplicated to_pci_dev() conversion

In pci_msi_update_mask(), "lock = &to_pci_dev()" does the to_pci_dev()
lookup, and there's another one buried inside msi_desc_to_pci_dev().

Introduce a local variable to remove that duplication.

Signed-off-by: Chris Li <chrisl@kernel.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Link: https://lore.kernel.org/all/20250617-pci-msi-avoid-dup-pcidev-v1-1-ed75b0419023@kernel.org