i2c: nuvoton: remove standard mode only

first version is only support standard mode.
remove this judgment to support standard/fast/fast plus  mode.

Signed-off-by: Jim Liu <JJLIU0@nuvoton.com>

Changes for v2:
   - add commit message
Reviewed-by: Heiko Schocher <hs@denx.de>
1 file changed