hw/block: Add Microchip's 25CSM04 to m25p80

hw/block: Add Microchip's 25CSM04 to m25p80

Add Microchip's 25CSM04 Serial EEPROM to m25p80.  25CSM04 provides 4 Mbits
of Serial EEPROM utilizing the Serial Peripheral Interface (SPI) compatible
bus. The device is organized as 524288 bytes of 8 bits each (512Kbyte) and
is optimized for use in consumer and industrial applications where reliable
and dependable nonvolatile memory storage is essential.

Signed-off-by: Chalapathi V <chalapathi.v@linux.ibm.com>
Reviewed-by: Glenn Miles <milesg@linux.ibm.com>
Reviewed-by: Cédric Le Goater <clg@kaod.org>
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>