m32r: fix build warning about putc

We were getting build warning:

  arch/m32r/boot/compressed/m32r_sio.c:11:13:
     warning: conflicting types for built-in function 'putc'

Here putc is used as a static function so lets just rename it to avoid
the conflict with the builtin putc.

Link: http://lkml.kernel.org/r/1466977046-24724-1-git-send-email-sudipm.mukherjee@gmail.com
Signed-off-by: Sudip Mukherjee <sudip.mukherjee@codethink.co.uk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

arch/m32r/boot/compressed/m32r_sio.c

@@ -8,12 +8,13 @@
 
 #include <asm/processor.h>
 
-static void putc(char c);
+static void m32r_putc(char c);
 
 static int puts(const char *s)
 {
 	char c;
-	while ((c = *s++)) putc(c);
+	while ((c = *s++))
+		m32r_putc(c);
 	return 0;
 }
 
@@ -41,7 +42,7 @@ static int puts(const char *s)
 #define BOOT_SIO0TXB	PLD_ESIO0TXB
 #endif
 
-static void putc(char c)
+static void m32r_putc(char c)
 {
 	while ((*BOOT_SIO0STS & 0x3) != 0x3)
 		cpu_relax();
@@ -61,7 +62,7 @@ static void putc(char c)
 #define SIO0TXB	(volatile unsigned short *)(0x00efd000 + 30)
 #endif
 
-static void putc(char c)
+static void m32r_putc(char c)
 {
 	while ((*SIO0STS & 0x1) == 0)
 		cpu_relax();