drm: renesas: rzg2l_mipi_dsi: Increase reset deassertion delay

drm: renesas: rzg2l_mipi_dsi: Increase reset deassertion delay

The RZ/G2L hardware manual (Rev. 1.50, May 2025), Section 34.4.2.1,
requires waiting at least 1 msec after deasserting the CMN_RSTB signal
before the DSI-Tx module is ready. Increase the delay from 1 usec to
1 msec by replacing udelay(1) with fsleep(1000) for RZ/G2L SoCs.

Fixes: 7a043f978ed1 ("drm: rcar-du: Add RZ/G2L DSI driver")
Cc: stable@vger.kernel.org
Reviewed-by: Tommaso Merciai <tommaso.merciai.xr@bp.renesas.com>
Tested-by: Tommaso Merciai <tommaso.merciai.xr@bp.renesas.com>
Link: https://patch.msgid.link/20260330104450.128512-3-biju.das.jz@bp.renesas.com
Signed-off-by: Biju Das <biju.das.jz@bp.renesas.com>