cbmem console: expose empty functions

In order to not have to guard cbmem console calls provide
empty implementations.

BUG=None
BRANCH=None
TEST=Able to build with call to cbmemc_reinit() without having
     CONSOLE_CBMEM enabled.

Change-Id: Ib26f2d66f2a431fe53c7b9fc2dd03fc7168d8e75
Signed-off-by: Aaron Durbin <adurbin@chromium.org>
Reviewed-on: https://chromium-review.googlesource.com/207580
Reviewed-by: Furquan Shaikh <furquan@chromium.org>

src/include/console/cbmem_console.h

@@ -19,8 +19,13 @@
 #ifndef _CONSOLE_CBMEM_CONSOLE_H_
 #define _CONSOLE_CBMEM_CONSOLE_H_
 
+#if IS_ENABLED(CONFIG_CONSOLE_CBMEM)
 void cbmemc_init(void);
 void cbmemc_reinit(void);
 void cbmemc_tx_byte(unsigned char data);
+#else
+static inline void cbmemc_init(void) {}
+static inline void cbmemc_reinit(void) {}
+#endif
 
 #endif

src/include/console/console.h

@@ -33,9 +33,7 @@
 #if CONFIG_CONSOLE_NE2K
 #include <console/ne2k.h>
 #endif
-#if CONFIG_CONSOLE_CBMEM
 #include <console/cbmem_console.h>
-#endif
 
 #ifndef __PRE_RAM__
 unsigned char console_rx_byte(void);