arm: Fix arm_simd_types and MVE scalar_types

arm: Fix arm_simd_types and MVE scalar_types

So far we define arm_simd_types and scalar_types using type
definitions like intSI_type_node, etc...

This is causing problems with later patches which re-implement
load/store MVE intrinsics, leading to error messages such as:
  error: passing argument 1 of 'vst1q_s32' from incompatible pointer type
  note: expected 'int *' but argument is of type 'int32_t *' {aka 'long int *'}

This patch uses get_typenode_from_name (INT32_TYPE) instead, which
defines the types as appropriate for the target/C library.

2023-11-16  Christophe Lyon  <christophe.lyon@linaro.org>

	gcc/
	* config/arm/arm-builtins.cc (arm_init_simd_builtin_types): Fix
	initialization of arm_simd_types[].eltype.
	* config/arm/arm-mve-builtins.def (DEF_MVE_TYPE): Fix scalar
	types.