mtd: mtk-nor: Drop bogus __init from mtk_nor_init()

WARNING: drivers/mtd/spi-nor/mtk-quadspi.o(.text+0x77e): Section mismatch in reference from the function mtk_nor_drv_probe() to the function .init.text:mtk_nor_init()
The function mtk_nor_drv_probe() references
the function __init mtk_nor_init().
This is often because mtk_nor_drv_probe lacks a __init
annotation or the annotation of mtk_nor_init is wrong.

Drop the bogus __init from mtk_nor_init() to kill this warning.

Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org>
Signed-off-by: Brian Norris <computersforpeace@gmail.com>