Kconfig: enable building for RISCV_ISA_RV32E

It is possible to build for that target with nightly and
standard library built from source.

Author: masz-nordic

Kconfig

@@ -8,7 +8,7 @@ menu "Rust Language Support"
 config RUST_SUPPORTED
 	bool
 	default y if ((CPU_CORTEX_M || \
-				(RISCV && !RISCV_ISA_RV32E && !RISCV_ISA_RV128I) || \
+				(RISCV && !RISCV_ISA_RV128I) || \
 				(ARCH_POSIX && 64BIT)) && \
 				!TIMER_READS_ITS_FREQUENCY_AT_RUNTIME)
 	help