ARM: keystone: remove redundant reset stuff

Remove reset stuff in flavour of using keystone reset driver:
driver/power/reset/keystone-reset.c

Reviewed-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Ivan Khoronzhuk <ivan.khoronzhuk@ti.com>
Signed-off-by: Santosh Shilimkar <santosh.shilimkar@ti.com>