bootm: move lmb into the bootm_headers_t structure

To allow for persistent state between future bootm subcommands we
need the lmb to exist in a global state.
Moving it into the bootm_headers_t allows us to do that.

Signed-off-by: Kumar Gala <galak@kernel.crashing.org>
diff --git a/lib_m68k/bootm.c b/lib_m68k/bootm.c
index 241721d..1c3b9c9 100644
--- a/lib_m68k/bootm.c
+++ b/lib_m68k/bootm.c
@@ -58,7 +58,7 @@
 	ulong bootmap_base;
 	bd_t  *kbd;
 	void  (*kernel) (bd_t *, ulong, ulong, ulong, ulong);
-	struct lmb *lmb = images->lmb;
+	struct lmb *lmb = &images->lmb;
 
 	bootmap_base = getenv_bootm_low();