ACPI: NUMA: Remove unnecessary check in acpi_parse_gi_affinity()

The acpi_map_pxm_to_node() function will never return a node value
that is greater than or equal to MAX_NUMNODES. Remove the unnecessary
`node >= MAX_NUMNODES` check to keep the code consistent with other users
of the acpi_map_pxm_to_node() function.

Signed-off-by: Yuntao Wang <ytcoode@gmail.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>