extmod/modplatform: Distinguish RISC-V 64 from RISC-V 32.

This commit lets the platform module report a more accurate architecture
name when running on a RISC-V 64 bits platform.

Signed-off-by: Alessandro Gatti <[email protected]>

Author: agatti

extmod/modplatform.h

@@ -48,7 +48,11 @@
 #elif defined(__xtensa__)
 #define MICROPY_PLATFORM_ARCH   "xtensa"
 #elif defined(__riscv)
+#if __riscv_xlen == 64
+#define MICROPY_PLATFORM_ARCH   "riscv64"
+#else
 #define MICROPY_PLATFORM_ARCH   "riscv"
+#endif
 #else
 #define MICROPY_PLATFORM_ARCH   ""
 #endif