drm/bridge: tc358775: Do not soft reset i2c-slave controller

Soft reset during tc_bridge_enable() is triggered by setting all available
reset control bits in the SYSRST register.
But as noted in the data sheet resetting the i2c-slave controller should
be only done over DSI and is only useful for chip debugging.
So do not set RSTI2CS (bit0).

Signed-off-by: Teresa Remmet <t.remmet@phytec.de>
Reviewed-by: Robert Foss <robert.foss@linaro.org>
Signed-off-by: Robert Foss <robert.foss@linaro.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20220901131951.1116512-1-t.remmet@phytec.de