lmb: Correctly unmap memory after notifications

We never unmap the memory used to update the EFI memory map after
notifications

Fixes: commit 2f6191526a ("lmb: notify of any changes to the LMB memory map")
Signed-off-by: Ilias Apalodimas <ilias.apalodimas@linaro.org>
Reviewed-by: Heinrich Schuchardt <xypron.glpk@gmx.de>

lib/lmb.c

@@ -65,6 +65,7 @@ static int __maybe_unused lmb_map_update_notify(phys_addr_t addr,
 			status & ~EFI_ERROR_MASK);
 		return -1;
 	}
+	unmap_sysmem((void *)(uintptr_t)efi_addr);
 
 	return 0;
 }