spl: remove dependency to "asm/utils.h"

Header file "asm/utils.h" is not required to compile "spl_ymodem.c".
So, removing this dependency allows other architectures to use this
booting device as "asm/utils.h" is only present in "arm" architecture.

Signed-off-by: Paulo Zaneti <paulo.zaneti@datacom.ind.br>
diff --git a/common/spl/spl_ymodem.c b/common/spl/spl_ymodem.c
index 35f8f80..3b1bd71 100644
--- a/common/spl/spl_ymodem.c
+++ b/common/spl/spl_ymodem.c
@@ -12,7 +12,6 @@
 #include <spl.h>
 #include <xyzModem.h>
 #include <asm/u-boot.h>
-#include <asm/utils.h>
 #include <linux/libfdt.h>
 
 #define BUF_SIZE 1024