nfc: s3fwrn5: reduce the EN_WAIT_TIME

The delay of 20ms is enough to enable and
wake up the Samsung's nfc chip.

Acked-by: Krzysztof Kozlowski <krzk@kernel.org>
Signed-off-by: Bongsu Jeon <bongsu.jeon@samsung.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>