MIPS: lantiq: Fix typo in a comment

The double `if' in the comment in line 144 is repeated. Remove one
of them from the comment.
Signed-off-by: Jason Wang <wangborong@cdjrlc.com>
Signed-off-by: Thomas Bogendoerfer <tsbogend@alpha.franken.de>

arch/mips/lantiq/falcon/sysctrl.c

@@ -141,7 +141,7 @@ static void falcon_gpe_enable(void)
 	unsigned int freq;
 	unsigned int status;
 
-	/* if if the clock is already enabled */
+	/* if the clock is already enabled */
 	status = sysctl_r32(SYSCTL_SYS1, SYS1_INFRAC);
 	if (status & (1 << (GPPC_OFFSET + 1)))
 		return;