Rename getenv_r() into getenv_f()

While running from flash, i. e. before relocation, we have only a
limited C runtime environment without writable data segment. In this
phase, some configurations (for example with environment in EEPROM)
must not use the normal getenv(), but a special function.  This
function had been called getenv_r(), with the idea that the "_r"
suffix would mean the same as in the _r_eentrant versions of some of
the C library functions (for example getdate vs. getdate_r, getgrent
vs. getgrent_r, etc.).

Unfortunately this was a misleading name, as in U-Boot the "_r"
generally means "running from RAM", i. e. _after_ relocation.

To avoid confusion, rename into getenv_f() [as "running from flash"]

Signed-off-by: Wolfgang Denk <wd@denx.de>
Acked-by: Detlev Zundel <dzu@denx.de>
diff --git a/include/common.h b/include/common.h
index eddec22..6a79ec2 100644
--- a/include/common.h
+++ b/include/common.h
@@ -256,7 +256,7 @@
 void	env_relocate (void);
 int	envmatch     (uchar *, int);
 char	*getenv	     (char *);
-int	getenv_r     (char *name, char *buf, unsigned len);
+int	getenv_f     (char *name, char *buf, unsigned len);
 int	saveenv	     (void);
 #ifdef CONFIG_PPC		/* ARM version to be fixed! */
 int inline setenv   (char *, char *);