irqchip/ls-scfg-msi: Simplify Kconfig dependencies

Having both PCI_MSI and PCI is redundant. Drop PCI.

Signed-off-by: Lukas Bulwahn <lukas.bulwahn@gmail.com>
[maz: cut commit message extra verbosity]
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20230111100554.24500-1-lukas.bulwahn@gmail.com