temp/iio-sensor-proxy: only build on aarch64 (MR 4955)

Instead of just disabling it on armv7, we can only build it on aarch64
given that the patches applied only are relevant on that architecture
anyway.

[ci:skip-vercheck]: No need to increment pkgrel when only changing
architectures.
[ci:skip-build]: already built successfully in CI

temp/iio-sensor-proxy/APKBUILD

@@ -5,7 +5,7 @@ pkgver=9999
 pkgrel=1
 pkgdesc="IIO sensors to D-Bus proxy"
 url="https://gitlab.freedesktop.org/hadess/iio-sensor-proxy"
-arch="all !armv7"
+arch="aarch64"
 license="GPL-2.0-or-later"
 depends="dbus"
 makedepends="