lib:lmb: use __weak

This not only looks a bit better it also prevents a
warning with W=1 (no previous prototype).

Signed-off-by: Jeroen Hofstee <jeroen@myspectrum.nl>

lib/lmb.c

@@ -332,14 +332,12 @@ int lmb_is_reserved(struct lmb *lmb, phys_addr_t addr)
 	return 0;
 }
 
-void __board_lmb_reserve(struct lmb *lmb)
+__weak void board_lmb_reserve(struct lmb *lmb)
 {
 	/* please define platform specific board_lmb_reserve() */
 }
-void board_lmb_reserve(struct lmb *lmb) __attribute__((weak, alias("__board_lmb_reserve")));
 
-void __arch_lmb_reserve(struct lmb *lmb)
+__weak void arch_lmb_reserve(struct lmb *lmb)
 {
 	/* please define platform specific arch_lmb_reserve() */
 }
-void arch_lmb_reserve(struct lmb *lmb) __attribute__((weak, alias("__arch_lmb_reserve")));