realtek: fix Linksys LGS328C dts memory definition

realtek: fix Linksys LGS328C dts memory definition

RTL930x devices have highmem starting address at 0x20000000.
The Linksys LGS328C highmem definition is wrongly shared with
the larger LGS352C RTL931x model and starts at 0x90000000.
Fix it by splitting the definition.

Fixes: 853d73f ("realtek: add support for Linksys LGS328C")
Signed-off-by: Markus Stockhausen <markus.stockhausen@gmx.de>
Link: https://github.com/openwrt/openwrt/pull/21262
Signed-off-by: Hauke Mehrtens <hauke@hauke-m.de>
(cherry picked from commit 5d7470d4caab5c4c9b0d9e853d4681f2e7183c4e)