irqchip: armada-370-xp: fix invalid cast of signed value into unsigned variable

irqchip: armada-370-xp: fix invalid cast of signed value into unsigned variable

commit da343fc776e0bcb238b65d9d24610819b95d0ef4 upstream.

The armada_370_xp_alloc_msi() function returns a signed int, which is
negative on error. However, we store the return value into an
irq_hw_number_t, which is unsigned. Therefore, we actually never test
if armada_370_xp_alloc_msi() returns an error or not, which may lead
us to use hwirq numbers of as 0xffffffe4 (when
armada_370_xp_alloc_msi() returns -ENOSPC).

This commit fixes that by storing the return value of
armada_370_xp_alloc_msi() in a signed variable.

Fixes: 31f614edb726fcc4d5aa0f2895fbdec9b04a3ca4 ('irqchip: armada-370-xp: implement MSI support')
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
Link: https://lkml.kernel.org/r/1397823593-1932-2-git-send-email-thomas.petazzoni@free-electrons.com
Tested-by: Neil Greatorex <neil@fatboyfat.co.uk>
Signed-off-by: Jason Cooper <jason@lakedaemon.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>