PCI: mobiveil: Fix infinite-loop in the INTx handling function

In the loop handling INTx interrupts in mobiveil_pcie_isr(), there is
no code to update the loop control variable, which is causing an
infinite loop.

Fix the code by reading the interrupt status registers inside the
loop.

Fixes: 9af6bcb1 ("PCI: mobiveil: Add Mobiveil PCIe Host Bridge IP driver")
Signed-off-by: Hou Zhiqiang <Zhiqiang.Hou@nxp.com>
Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Reviewed-by: Minghuan Lian <Minghuan.Lian@nxp.com>
Reviewed-by: Subrahmanya Lingappa <l.subrahmanya@mobiveil.co.in>
Acked-by: Karthikeyan Mitran <m.karthikeyan@mobiveil.co.in>
Tested-by: Karthikeyan Mitran <m.karthikeyan@mobiveil.co.in>