ARM: davinci_all_defconfig: Enable AEMIF as a module

This enables the use of the memory/ti-aemif.c driver.
ATM most davinci boards use the mach-davinci aemif code which gets in
the way of genericity and proper DT boot.

Signed-off-by: Karl Beldan <kbeldan@baylibre.com>
Signed-off-by: Sekhar Nori <nsekhar@ti.com>