realtek: rt-loader: fix RTL839x/RTL93xx version detection

realtek: rt-loader: fix RTL839x/RTL93xx version detection

There is a misunderstanding of the chip version detection in the
rt-loader. For all SoCs the data is gathered from the registers
MODEL_NAME_INFO and CHIP_INFO. Sadly the bits are shuffled around
with each hardware. Currently the loader gathers the wrong bits
for RTL839x and RTL93xx. Fix that.

While we are here write the if statements vice versa for better
readability and give some variables better names. Align the
ouput with that from the kernel.

Fixes: ccbff8b ("realtek: add rt-loader (runtime loader)"
Signed-off-by: Markus Stockhausen <markus.stockhausen@gmx.de>
Link: https://github.com/openwrt/openwrt/pull/21994
Signed-off-by: Robert Marko <robimarko@gmail.com>