refactor(gicv3): add helper function to get the limit of SPI INTID

Add helper function gicv3_get_spi_limit() to get the value of (maximum
SPI INTID + 1), so that some duplicated code can be removed later.

Signed-off-by: Heyi Guo <guoheyi@linux.alibaba.com>
Change-Id: I160c8a88fbb71d22790b8999a84afbfba766f5e7
2 files changed