[PATCH net-next] drivers: net: xgene: Fix the compilation error "error: implicit declaration of function 'acpi_evaluate_integer'" for CONFIG_ACPI=n.

From: Suman Tripathi <redacted>
Date: Mon,  6 Jul 2015 13:34:22 +0530

This patch guards the acpi_evaluate_interger function as it fails
the build for CONFIG_ACPI=n.

Signed-off-by: Iyappan Subramanian <redacted>
Signed-off-by: Suman Tripathi <redacted>
Reported-by: kbuild test robot <redacted>

While the net-next tree is closed, all work and bug fixes should occur against
'net' which trumps the 'net-next' tree during this time.

If you had investigated, you would have seen that this build failure had
been fixed in the 'net' tree for some time now.