clk: Make x86/ conditional on CONFIG_COMMON_CLK

commit f35b6542c3ac3f28056d298348a81f7d56d3a041 upstream.

Fix Makefile for x86 support, dependency on CONFIG_COMMON_CLK
was not explicit

Fixes: 701190fd ('clk: x86: add support for Lynxpoint LPSS clocks')
Signed-off-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
Acked-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>