common: Drop log.h from common header

Move this header out of the common header.

Signed-off-by: Simon Glass <sjg@chromium.org>
diff --git a/arch/arm/lib/semihosting.c b/arch/arm/lib/semihosting.c
index 1b365a9..904fddd 100644
--- a/arch/arm/lib/semihosting.c
+++ b/arch/arm/lib/semihosting.c
@@ -14,6 +14,7 @@
 #include <common.h>
 #include <command.h>
 #include <env.h>
+#include <log.h>
 
 #define SYSOPEN		0x01
 #define SYSCLOSE	0x02