raspberry-rpi: fix use of deprecated initramfs-<flavor> (MR 3225)

This is the same as c8b3a16e38, but
for the original Raspbberry Pi.

Related to !2731

device/testing/device-raspberry-pi/APKBUILD

@@ -1,8 +1,8 @@
 # Reference: <https://postmarketos.org/devicepkg>
 pkgname=device-raspberry-pi
 pkgdesc="Raspberry Pi"
-pkgver=0.1
-pkgrel=17
+pkgver=0.2
+pkgrel=0
 url="https://postmarketos.org"
 license="MIT"
 arch="armhf"
@@ -65,7 +65,7 @@ phosh() {
 
 sha512sums="
 f1ee1275f72805f6b04a9b7a111d0111b96c3df37dbff565add99b0007a6e4fecc781a4599b439f2c8308ec5db9db66ae2e6f0db66d9db3327b3013b347474f0  deviceinfo
-501b085650a7c1e39628b64c6bf05e967f08470c9c70c648ce45b5cdf05e831b994f91e91ba83ad076797deb7ee405ff4912bcd71779d66b7056d1786d366a3c  config.txt
+f70469c3dca65f39ff041af9983eae3b87080fcfb1f8fddb3f58b5a477f708f758f64d46b2195a5bef8d3fa03894e1bf0a427fec5e138d57549392e5b9a6e589  config.txt
 e94c810f973eb6b6d0fb3687ea1d70612ba00e9c5d6b3608390a161e077c5591fd9d232c37b42443c05ed28bb639ca1754422ff35899c5e33d7fc266e0e1ad05  usercfg.txt
 ae3de0b8fec07d3a283dc3c06bf8678eec1e65c9faf0b7f4fdc9fb92751e324d1f8e2fb224dbbf561b7e5a6fb34769bfa1657858375f74b101a130d78e0737e2  cmdline.txt
 7e5505cb07d5b4a81bd28443d508336b5c547356538f1c06f91ed93ad0d7d456d4f74f1d24df5a2e08c17e74f0a66607352ac4874e967e9a91dfec9522d2d58d  95-vchiq-permissions.rules

device/testing/device-raspberry-pi/config.txt

@@ -5,15 +5,15 @@ gpu_mem_256=64
 dtoverlay=vc4-kms-v3d
 [pi0]
 kernel=vmlinuz-rpi
-initramfs initramfs-rpi
+initramfs initramfs
 [pi1]
 kernel=vmlinuz-rpi
-initramfs initramfs-rpi
+initramfs initramfs
 [pi2]
 kernel=vmlinuz-rpi2
-initramfs initramfs-rpi2
+initramfs initramfs
 [pi3]
 kernel=vmlinuz-rpi2
-initramfs initramfs-rpi2
+initramfs initramfs
 [all]
 include usercfg.txt