py/emitglue: Fix clear cache builtin warning on Clang for AArch32.

This commit fixes a warning occurring on Clang when calling
`__builtin___clear_cache` with non-void pointers for its start and end
memory area locations.  The code now uses a char pointer for the end
location, and it still builds without warnings on GCC.

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

Author: agatti

py/emitglue.c

@@ -115,7 +115,7 @@ void mp_emit_glue_assign_native(mp_raw_code_t *rc, mp_raw_code_kind_t kind, cons
     #endif
     #elif MICROPY_EMIT_ARM
     #if (defined(__linux__) && defined(__GNUC__)) || __ARM_ARCH == 7
-    __builtin___clear_cache((void *)fun_data, (uint8_t *)fun_data + fun_len);
+    __builtin___clear_cache((void *)fun_data, (char *)fun_data + fun_len);
     #elif defined(__arm__)
     // Flush I-cache and D-cache.
     asm volatile (