Since commit c7cc27d006cc (clk: mux: Support CLK_MUX_READ_ONLY flag)
Barebox defines the CLK_MUX_READ_ONLY flag like Linux.

The ZynqMP clock driver used the flag before, because this flag is used
to convey this information from the PMU firmware to the Linux driver.
However, the flags of the common clock framework and the flag of the
protocol between PMU firmware and the ZynqMP clock driver should be
handled separately.

Therefore, add a driver specific prefix to the flag definition in the
ZynqMP driver.

Fixes the warning

	drivers/clk/zynqmp/clk-mux-zynqmp.c:18:0: warning: "CLK_MUX_READ_ONLY" redefined
	In file included from drivers/clk/zynqmp/clk-mux-zynqmp.c:13:0:
	include/linux/clk.h:350:0: note: this is the location of the previous definition

Signed-off-by: Michael Tretter <m.tretter@pengutronix.de>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>