treewide: fix "followings" to "following"

Most of them are my mistakes.

Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
diff --git a/doc/README.kconfig b/doc/README.kconfig
index 288d17d..0689f66 100644
--- a/doc/README.kconfig
+++ b/doc/README.kconfig
@@ -22,7 +22,7 @@
 - silentoldconfig
 
   This target updates .config, include/generated/autoconf.h and
-  include/configs/* as in Linux.  In U-Boot, it also does the followings
+  include/configs/* as in Linux.  In U-Boot, it also does the following
   for the compatibility with the old configuration system:
 
    * create a symbolic link "arch/${ARCH}/include/asm/arch" pointing to