eeprom: at25: allow page sizes greater than 16 bit

Storage technologies like FRAM have no "write pages", the whole chip can
be written within one SPI transfer. For these chips, the page size can
be set equal to the device size. Currently available devices are already
bigger than 64 kiB.

Signed-off-by: Christian Eggers <ceggers@arri.de>
Link: https://lore.kernel.org/r/20200727111218.26926-1-ceggers@arri.de


Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>