lmb: Add support of flags for no-map properties

Add "flags" in lmb_property to save the "no-map" property of
reserved region and a new function lmb_reserve_flags() to check
this flag.

The default allocation use flags = LMB_NONE.

The adjacent reserved memory region are merged only when they have
the same flags value.

This patch is partially based on flags support done in Linux kernel
mm/memblock .c (previously lmb.c); it is why LMB_NOMAP = 0x4, it is
aligned with MEMBLOCK_NOMAP value.

Signed-off-by: Patrick Delaunay <patrick.delaunay@foss.st.com>
Reviewed-by: Simon Glass <sjg@chromium.org>