mtd: spi-nor: Add support for Winbond w25q16dw

Add JEDEC entry for the Winbond w25q16fw/w25q16dw with similar
flags and format than the Winbond w25q32dw entry.

Tested on a Khadas VIM2 SBC board with an Amlogic S912 SoC.

Signed-off-by: Neil Armstrong <narmstrong@baylibre.com>
Signed-off-by: Cyrille Pitchen <cyrille.pitchen@wedev4u.fr>