staging: emxx_udc: Fix build error

‘strict_strtol’ is deprecated. Use kstrtol instead. Fixes the following
build error:
drivers/staging/emxx_udc/emxx_udc.c:3288:3: error: implicit declaration of function ‘strict_strtol’

Signed-off-by: Sachin Kamat <sachin.kamat@samsung.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>