MAINTAINERS: remove Tudor Ambarus as SPI NOR maintainer

I have not been actively involved in SPI NOR development recently and
would like to step down to focus on my current day-to-day work.

The subsystem remains in good hands with Pratyush and Michael.

Signed-off-by: Tudor Ambarus <tudor.ambarus@linaro.org>
Acked-by: Michael Walle <mwalle@kernel.org>
Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>

Author: ambarus

MAINTAINERS

@@ -24909,7 +24909,6 @@ F:	drivers/clk/spear/
 F:	drivers/pinctrl/spear/
 
 SPI NOR SUBSYSTEM
-M:	Tudor Ambarus <tudor.ambarus@linaro.org>
 M:	Pratyush Yadav <pratyush@kernel.org>
 M:	Michael Walle <mwalle@kernel.org>
 L:	linux-mtd@lists.infradead.org