ARM: omap2plus_defconfig: enable support for M25P80 SPI NOR

M25P80 driver provides support for most common SPI NOR devices.
These devices are commonly found on TI EVMs for AM437x and DRA7x
SoCs.

Enable support for this driver in defconfig for omap2plus devices.

Signed-off-by: Sekhar Nori <nsekhar@ti.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>