[PATCH v3] arm: rust: Enable Rust support for ARMv7

[Manish Shakya]

Tested with Beaglebone back with following configs:

# zcat /proc/config.gz | grep RUST
CONFIG_RUSTC_VERSION=108600
CONFIG_RUST_IS_AVAILABLE=y
CONFIG_RUSTC_LLVM_VERSION=190107
CONFIG_RUST=y
CONFIG_RUSTC_VERSION_TEXT="rustc 1.86.0 (05f9846f8 2025-03-31)"
CONFIG_HAVE_RUST=y
# CONFIG_RUST_FW_LOADER_ABSTRACTIONS is not set
CONFIG_TRUSTED_FOUNDATIONS=y
# CONFIG_BLK_DEV_RUST_NULL is not set
# CONFIG_RUST_PHYLIB_ABSTRACTIONS is not set
# CONFIG_HID_THRUSTMASTER is not set
# CONFIG_TRUSTED_KEYS is not set
CONFIG_SYSTEM_TRUSTED_KEYRING=y
CONFIG_SYSTEM_TRUSTED_KEYS=""
# CONFIG_SECONDARY_TRUSTED_KEYRING is not set
CONFIG_RUST_DEBUG_ASSERTIONS=y
CONFIG_RUST_OVERFLOW_CHECKS=y
CONFIG_RUST_BUILD_ASSERT_ALLOW=y