rock-s0: drop u-boot v1.1 MMC patch that can't apply to v2026.07

The carried board patch 1120-mmcBootOnRockS0v1-1 fails to apply on v2026.07
(Hunk #1 FAILED at 5), aborting the whole uboot-rock-s0 build. u-boot restructured
rk3308-rock-s0-u-boot.dtsi (already in v2025.04+): the node was renamed
&sdmmc -> &sdmmc_2030 and new nodes (&gpio4, &sdmmc_2030) were inserted, so the
patch context no longer matches. Upstream now also ships
`&sdmmc_2030 { bootph-pre-ram; }`, covering the core SPL sdmmc access the patch
was mainly for.

A correct rebase would need the renamed node + verified pinctrl labels and, since
it's a Rock S0 v1.1 hardware fix (pwren RK_PD6 pull-down), validation on a v1.1
board — maintainer territory. Drop it for now so rock-s0 builds on v2026.07
(v2024.10 doesn't build on trixie at all). The only thing lost vs upstream is the
v1.1-specific SD pwren override.

@brentr: if Rock S0 v1.1 boards regress on SD/SPL boot, the pwren override needs
re-rebasing onto v2026.07's &sdmmc_2030 + verified pinctrl labels.

Signed-off-by: Igor Pecovnik <igor@armbian.com>

Author: igorpecovnik