turny: fix SPI/GPIO config for newer kernels

- Add complete config.txt settings with u-boot boot lines + spi=on
- Override sdImage.populateFirmwareCommands to use configtxt module output
- Mount firmware partition and add activation script to sync config.txt
- Load spi_bcm2835 and bcm2835_gpiomem kernel modules
- Add udev rule for gpiomem subsystem (not just gpio)
- Relax ProtectKernelTunables so service can access GPIO
- Update turny flake input to rppal-based CS pin fix

secrets/glance/reddit/app-id.age

@@ -1,10 +1,9 @@
 age-encryption.org/v1
--> ssh-ed25519 osOCZA wVGyI0bVEaVUbXMiumjhqdno2VD6ZHmvJM0NRUoesk0
-kW8Zs6KV+KBmyg/imOzVHHPg/K3oHyB05ayMQsT01CQ
--> ssh-ed25519 DFiohQ h+C13tChA1OrCdmJO9rkjW3ER/d8OW7P2IGd5spsd2Y
-7LOIjam4k8lmglNEuNs7lkRpt3UbYkxFxXPwkj2Fbc8
--> ssh-ed25519 PT7ffg 33/HLpIkjfw+QC1qm1Tmr4YqMjgtt4bsVoFqUNinhno
-8+PGKzffQT2DuM8l9mqgGieHiQCpBsbWbHDIdxFapBk
---- lzyw/qQSELbYc8TWYFGD57JBF4JorTLhBPNdlxYjVqY
-lÞHºaEM9ÅóüÀS0(Š¥¦lâJxø-
-—sÔ¸éžc¬H	EÖ˜Í0_{|K‚p2
+-> ssh-ed25519 osOCZA X80qdaNMdIz7sy+tLmTYlati/SKucc03gW5FXE9/xlM
+5ZvMFxd3MOl4SyBEYR9xawjREi8UwEmW9DyuCC+E8jk
+-> ssh-ed25519 DFiohQ NPghTlceQTcZh4VGASPeFZy8G2VLURxykc0JjvAdW2s
+MkIN+sOI3yD8UzSmHOabeVnFHfXDDWMSWwFIuHGJGFE
+-> ssh-ed25519 PT7ffg mc6TmlrgBEBQeOECY6SzHaLhpi4SrYc/9m9nml/2GGY
+VDNZtQSSGG1+/84Y5TcyiJytoAoPCyj9PlYV7WZiKE8
+--- GPLaSoO3+AZXfY9gIweM+dDAb+hBSadz++DqYEkR2ug
+;ܬl‘öj…Ãå˜æ?çÚøÆQ²
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