PCI: fu740: Set the number of MSI vectors

The iMSI-RX module of the DW PCIe controller provides multiple sets of
MSI_CTRL_INT_i_* registers, and each set is capable of handling 32 MSI
interrupts. However, the fu740 PCIe controller driver only enabled one set
of MSI_CTRL_INT_i_* registers, as the total number of supported interrupts
was not specified.

Set the supported number of MSI vectors to enable all the MSI_CTRL_INT_i_*
registers on the fu740 PCIe core, allowing the system to fully utilize the
available MSI interrupts.

Link: https://lore.kernel.org/r/20230807055621.2431-1-yongxuan.wang@sifive.com


Signed-off-by: Yong-Xuan Wang <yongxuan.wang@sifive.com>
Signed-off-by: Lorenzo Pieralisi <lpieralisi@kernel.org>
Reviewed-by: Serge Semin <fancer.lancer@gmail.com>