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/board/Marvell/db64460/mv_eth.c b/board/Marvell/db64460/mv_eth.c
index 58b63a3..cd9d5a4 100644
--- a/board/Marvell/db64460/mv_eth.c
+++ b/board/Marvell/db64460/mv_eth.c
@@ -248,7 +248,7 @@
 			return;
 		}
 
-		temp = getenv_r (s, buf, sizeof (buf));
+		temp = getenv_f(s, buf, sizeof (buf));
 		s = (temp > 0) ? buf : NULL;
 
 #ifdef DEBUG
@@ -350,7 +350,7 @@
 			return;
 		}
 
-		temp = getenv_r (s, buf, sizeof (buf));
+		temp = getenv_f(s, buf, sizeof (buf));
 		s = (temp > 0) ? buf : NULL;
 
 #ifdef DEBUG