drivers/elog: Fix implicit function declaration issue

Fix compilation. Relying on the pre-processor to condition an if
statement will lead to warnings of implicitly defined functions. To
solve this dilemma add symbols to resolve to at compile time.

Change-Id: Id0117528c5579cc1dec750a8a17a76fab4314b3f
Signed-off-by: Edward O'Callaghan <eocallaghan@alterapraxis.com>
Reviewed-on: http://review.coreboot.org/5504
Tested-by: build bot (Jenkins)
Reviewed-by: Alexandru Gagniuc <mr.nuke.me@gmail.com>

src/include/elog.h

@@ -162,7 +162,9 @@ extern u32 gsmi_exec(u8 command, u32 *param);
 #if CONFIG_ELOG_BOOT_COUNT
 u32 boot_count_read(void);
 u32 boot_count_increment(void);
-#endif
+#else
+static inline u32 boot_count_read(void) { return 0; }
+#endif /* CONFIG_ELOG_BOOT_COUNT */
 
 #endif /* !CONFIG_ELOG */
 

src/include/pc80/mc146818rtc.h

@@ -220,6 +220,8 @@ static inline enum cb_err get_option(void *dest __attribute__((unused)),
 #define CMOS_POST_EXTRA_DEV_PATH  0x01
 
 void cmos_post_log(void);
+#else
+static inline void cmos_post_log(void) {}
 #endif /* CONFIG_CMOS_POST */
 
 #endif /*  PC80_MC146818RTC_H */