net: ipa: cache last-saved GSI IRQ enabled type

Keep track of the set of GSI interrupt types that are currently
enabled by recording the mask value to write (or last written) to
the TYPE_IRQ_MSK register.

Create a new helper function gsi_irq_type_update() to handle
actually writing the register.

Signed-off-by: Alex Elder <elder@linaro.org>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>