ARM: keystone: aemif: move aemif driver to drivers/memory/ti-aemif.c

Move AEMIF driver to drivers/memory/ti-aemif.c along with AEMIF
definitions collected in arch/arm/include/asm/ti-common/ti-aemif.h

Acked-by: Vitaly Andrianov <vitalya@ti.com>
Signed-off-by: Ivan Khoronzhuk <ivan.khoronzhuk@ti.com>