Stop passing around bootmem_base value.

For the calls to boot_relocate_fdt(), boot_get_cmdline(), and
boot_get_kbd(), the value of bootmem_base is always obtained by
calling getenv_bootm_low().  Since the value always comes from the
same source, the calling signature for those functions can be
simplified by making them call getenv_bootm_low() directly.

Signed-off-by: Grant Likely <grant.likely@linaro.org>
diff --git a/common/cmd_bootm.c b/common/cmd_bootm.c
index 778f6a4..989bf73 100644
--- a/common/cmd_bootm.c
+++ b/common/cmd_bootm.c
@@ -547,8 +547,7 @@
 #if defined(CONFIG_OF_LIBFDT) && defined(CONFIG_SYS_BOOTMAPSZ)
 		case BOOTM_STATE_FDT:
 		{
-			ulong bootmap_base = getenv_bootm_low();
-			ret = boot_relocate_fdt(&images.lmb, bootmap_base,
+			ret = boot_relocate_fdt(&images.lmb,
 				&images.ft_addr, &images.ft_len);
 			break;
 		}