fix(sunxi-6.18): drop r-spi backport from series.conf

Follow-up to previous commit: also remove the now-deleted
patches.backports/31-clk_sunxi-ng_sun55i-a523-r_Add_missing_r-spi_module_clock.patch
entry from series.conf so the patcher does not look for a missing file.

Author: igorpecovnik

patch/kernel/archive/sunxi-6.18/series.conf

@@ -396,7 +396,6 @@
 	patches.backports/22-Enable-wifi-on-Radxa-Cubie-A5E.patch
 
 	patches.backports/30-allwinner-a523-support-spi-controllers.patch
-	patches.backports/31-clk_sunxi-ng_sun55i-a523-r_Add_missing_r-spi_module_clock.patch
 	patches.backports/32-pinctrl-sunxi-a523-Remove_unneeded_IRQ_remuxing_flag.patch
 	patches.backports/33-arm64-dts-allwinner-a523-Add_missing_GPIO_interrupt.patch
 	patches.backports/34-fix-wifi-regulator-cubie-a5e.patch