i3c: dw: replace ENOTSUPP with SUSV4-compliant EOPNOTSUPP

Replace non-standard ENOTSUPP with the SUSV4-defined error code
EOPNOTSUPP to fix below checkpatch warning:
  "ENOTSUPP is not a SUSV4 error code, prefer EOPNOTSUPP"

Signed-off-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
Reviewed-by: Frank Li <Frank.Li@nxp.com>
Link: https://lore.kernel.org/r/20250628192027.3932-7-wsa+renesas@sang-engineering.com


Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>