mtd: spi-nor: spansion: Rename s28hs512t prefix

Change prefix to support all other devices in SEMPER S28 family.

Signed-off-by: Takahiro Kuwano <Takahiro.Kuwano@infineon.com>
Signed-off-by: Tudor Ambarus <tudor.ambarus@microchip.com>
Reviewed-by: Michael Walle <michael@walle.cc>
Link: https://lore.kernel.org/r/8cf6bc9bffd50e486867c0817de1fa56c5d308ec.1661915569.git.Takahiro.Kuwano@infineon.com