arm: [MVE] Add missing __arm_vcvtnq_u32_f32 intrinsic (PR 96914)

arm: [MVE] Add missing __arm_vcvtnq_u32_f32 intrinsic (PR 96914)

__arm_vcvtnq_u32_f32 was missing from arm_mve.h, although the s32_f32 and
[su]16_f16 versions were present.

This patch adds the missing version and testcase, which are
cut-and-paste from the other versions.

2020-10-08  Christophe Lyon  <christophe.lyon@linaro.org>

	gcc/
	PR target/96914
	* config/arm/arm_mve.h (__arm_vcvtnq_u32_f32): New.

	gcc/testsuite/
	PR target/96914
	* gcc.target/arm/mve/intrinsics/vcvtnq_u32_f32.c: New test.

(cherry picked from commit 5a448362da6133c3b16ffdb0c795b657af7fa5a4)