[MTD] CHIPS: Support for SST 49LF040B flash chip

Add chip driver and JEDEC probe support for the SST 49LF040B flash chip.

Signed-off-by: Ryan Jackson <rjackson@lnxi.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: David Woodhouse <dwmw2@infradead.org>