Revert "mtd: spi-nor: Disable the flash quad mode in spi_nor_restore()"

Previous patch intends to restore the flash's QE bit when removed/shutdown,
but may have some problems and break the flash:

- for those originally in Quad mode, this patch will clear the QE bit
  when unloaded the flash, which is incorrect.
- even with above problem solved, it may still break the flash as some
  flash's QE bit is non-volatile and lots of set/reset will wear out
  the bit.
- the restore method cannot be proved to be valid as if a hard
  reset or accident crash happened, the spi_nor_restore() won't be
  performed the the QE bit will not be restored as we expected to.

So let's revert it to fix this. The discussion can be found at [1].

This reverts commit cc59e6bb.

[1] https://lore.kernel.org/linux-mtd/CAO8h3eFLVLRmw7u+rurKsg7=Nh2q-HVq-HgVXig8gf5Dffk8MA@mail.gmail.com/Reported-by: Matthias Weisser <m.weisser.m@gmail.com>
Suggested-by: Vignesh Raghavendra <vigneshr@ti.com>
Signed-off-by: Yicong Yang <yangyicong@hisilicon.com>
Signed-off-by: Vignesh Raghavendra <vigneshr@ti.com>
Link: https://lore.kernel.org/r/1599205640-26690-1-git-send-email-yangyicong@hisilicon.com

drivers/mtd/spi-nor/core.c

@@ -3000,8 +3000,6 @@ void spi_nor_restore(struct spi_nor *nor)
 	if (nor->addr_width == 4 && !(nor->flags & SNOR_F_4B_OPCODES) &&
 	    nor->flags & SNOR_F_BROKEN_RESET)
 		nor->params->set_4byte_addr_mode(nor, false);
-
-	spi_nor_quad_enable(nor, false);
 }
 EXPORT_SYMBOL_GPL(spi_nor_restore);