Fix show_boot_progress prototype

in commit fad634071 "make show_boot_progress () weak."
show_boot_progress is supposed to be declared as weak but declared as
inline instead.

Signed-off-by: Jean-Christophe PLAGNIOL-VILLARD <plagnioj@jcrosoft.com>

include/common.h

diff --git a/include/common.h b/include/common.h
index 11b7d31..fa1d052 100644
--- a/include/common.h
+++ b/include/common.h
@@ -661,7 +661,7 @@
 /*
  * Board-specific Platform code can reimplement show_boot_progress () if needed
  */
-void inline show_boot_progress (int val);
+void __attribute__((weak)) show_boot_progress (int val);
 
 #ifdef CONFIG_INIT_CRITICAL
 #error CONFIG_INIT_CRITICAL is deprecated!