serial: rsci: Convert to FIELD_MODIFY()

Use the FIELD_MODIFY() helper instead of open-coding the same operation.

Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Link: https://patch.msgid.link/ada3faf4698155a618ae6371b35eab121eb8b19c.1766411924.git.geert+renesas@glider.be
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
1 file changed