MAINTAINERS: add myself as a reviewer for the clk subsystem

I've reviewed a lot clk patches for parts of the subsystem that
typically doesn't get much review. Add myself as a reviewer so that I
don't miss anything.

Link: https://lore.kernel.org/linux-clk/?q=f%3Abmasney%40redhat.com
Signed-off-by: Brian Masney <bmasney@redhat.com>
Signed-off-by: Stephen Boyd <sboyd@kernel.org>

Author: masneyb

MAINTAINERS

@@ -6358,6 +6358,7 @@ F:	include/uapi/linux/comedi.h
 COMMON CLK FRAMEWORK
 M:	Michael Turquette <mturquette@baylibre.com>
 M:	Stephen Boyd <sboyd@kernel.org>
+R:	Brian Masney <bmasney@redhat.com>
 L:	linux-clk@vger.kernel.org
 S:	Maintained
 Q:	http://patchwork.kernel.org/project/linux-clk/list/