drivers: spi: ifx_cat1: drop non-existing DT properties

It looks like driver references quite a few non-existing properties in
devicetree (see dts/bindings/spi/infineon,cat1-spi.yml). This mistake
was hidden because of DT_INST_PROP_OR(), which expands to the default if
the property is not present. However, after
260fc896, the issue became visible
because sme DT_INST_PROP_OR() were changed to DT_INST_PROP().

Note that only fields not initialized to 0 (or false) have been kept.

Signed-off-by: Gerard Marull-Paretas <gerard@teslabs.com>