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/inka4x0/inka4x0.c b/board/inka4x0/inka4x0.c
index 27b79ec..fc498d6 100644
--- a/board/inka4x0/inka4x0.c
+++ b/board/inka4x0/inka4x0.c
@@ -187,7 +187,7 @@
 	char tmp[10];
 	int i, br;
 
-	i = getenv_r("brightness", tmp, sizeof(tmp));
+	i = getenv_f("brightness", tmp, sizeof(tmp));
 	br = (i > 0)
 		? (int) simple_strtoul (tmp, NULL, 10)
 		: CONFIG_SYS_BRIGHTNESS;