Unlike at24 (I2C), the at25 (spi) EEPROM driver doesn't check if the
device tree node contains partition definitions.  This means that one
for example cannot have bootstate partitions on an at25 EEPROM, while it
works on an at24 EEPROM.

This patch adds device tree based partition support to the at25 driver.

Signed-off-by: Harald Welte <laforge@gnumonks.org>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>