x86/platform/intel-mid: Unexport intel_mid_pci_set_power_state()

x86/platform/intel-mid: Unexport intel_mid_pci_set_power_state()

There's no module user of this.

Signed-off-by: Lukas Wunner <lukas@wunner.de>
Cc: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Cc: Bryan O'Donoghue <pure.logic@nexus-software.ie>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/b8cf9b508c89d3c69d20a61ff540e666d4243747.1477374931.git.lukas@wunner.de
Signed-off-by: Ingo Molnar <mingo@kernel.org>