mtd: spi-nor: micron-st: Add n25q064a WP support

mtd: spi-nor: micron-st: Add n25q064a WP support

These flash chips are used on Google / TP-Link / ASUS OnHub devices, and
OnHub devices are write-protected by default (same as any other
ChromeOS/Chromebook system). I've referred to datasheets, and tested on
OnHub devices.

Signed-off-by: Brian Norris <computersforpeace@gmail.com>
Reviewed-by: Michael Walle <mwalle@kernel.org>
Signed-off-by: Pratyush Yadav <pratyush@kernel.org>
Link: https://lore.kernel.org/r/20240726185825.142733-1-computersforpeace@gmail.com