ARM: zynq: pci: Modify xaxipcie.c read/write config to 32bit only

Some PCIe cards only support 32bit access to configuration space
and will return bogus values using 16 and 8 bit read/write accessors.
Modified arch/arm/mach-zynq/xaxipcie.c so the read_config and
write_config functions only use 32bits.

Modified arch/arm/mach-zynq/xaxipcie-msi.c to correctly keep track
of which MSI-X interrupts are allocated and deallocated.

Signed-off-by: Daniel M. Ladd <daniel.m.ladd@navy.mil>
Signed-off-by: Michal Simek <michal.simek@xilinx.com>