OMAP4: clock: fix compile warning

Fix the following compile warning:

arch/arm/mach-omap2/clock44xx_data.c: In function 'omap4xxx_clk_init':
arch/arm/mach-omap2/clock44xx_data.c:3371:6: warning: 'cpu_clkflg' may be used uninitialized in this function

The approach taken here is intended to work if omap4xxx_clk_init() is
converted into an initcall.

Thanks to Bjarne Steinsbo <bsteinsbo@gmail.com> for proposing another
approach.

Signed-off-by: Paul Walmsley <paul@pwsan.com>
Cc: Bjarne Steinsbo <bsteinsbo@gmail.com>

arch/arm/mach-omap2/clock44xx_data.c

@@ -3376,6 +3376,8 @@ int __init omap4xxx_clk_init(void)
 	} else if (cpu_is_omap446x()) {
 		cpu_mask = RATE_IN_4460;
 		cpu_clkflg = CK_446X;
+	} else {
+		return 0;
 	}
 
 	clk_init(&omap2_clk_functions);