drivers/intel/pmx_mux: Remove redundant declaration

Change-Id: Ie64b267ac01afa9774105e1ab8a7c18021726ff3
Signed-off-by: Kyösti Mälkki <kyosti.malkki@gmail.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/41871
Reviewed-by: Paul Menzel <paulepanter@users.sourceforge.net>
Reviewed-by: Tim Wawrzynczak <twawrzynczak@chromium.org>
Reviewed-by: Duncan Laurie <dlaurie@chromium.org>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>

src/drivers/intel/pmc_mux/chip.h

@@ -3,8 +3,6 @@
 #ifndef __DRIVERS_INTEL_PMC_MUX_H__
 #define __DRIVERS_INTEL_PMC_MUX_H__
 
-extern struct chip_operations drivers_intel_pmc_mux_ops;
-
 struct drivers_intel_pmc_mux_config {
 };