rust: pci: do not depend on CONFIG_PCI_MSI

rust: pci: do not depend on CONFIG_PCI_MSI

The PCI abstractions do not actually depend on CONFIG_PCI_MSI; it also
breaks drivers that only depend on CONFIG_PCI, hence drop it.

While at it, move the module entry to its correct location.

Reported-by: kernel test robot <lkp@intel.com>
Closes: https://lore.kernel.org/oe-kbuild-all/202501030744.4ucqC1cB-lkp@intel.com/
Fixes: 1bd8b6b2c5d3 ("rust: pci: add basic PCI device / driver abstractions")
Signed-off-by: Danilo Krummrich <dakr@kernel.org>
Link: https://lore.kernel.org/r/20250103164655.96590-2-dakr@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>