ARM: efm32: drop unused file <mach/timex.h>

This file is unused since commit

	79f08d9e (ARM: drop <mach/timex.h> for !ARCH_MULTIPLATFORM, too)

.
Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>

arch/arm/mach-efm32/include/mach/timex.h

-/*
- * Empty file waiting for deletion once <mach/timex.h> isn't needed any more.
- */