testsuite/arm: Remove useless -mfloat-abi option

testsuite/arm: Remove useless -mfloat-abi option

These tests pass with their current dg-add-options, no need to force
-mfloat=abi.

I've noticed no impact on armv8_1m-shift-imm-1.c and
armv8_1m-shift-reg-1.c, bf16_reinterpret.c now passes on
arm-linux-gnueabi and bf16_dup.c now passes on arm-linux-gnueabihf.

This allows pr51534.c to pass when forcing -mfloat-abi=soft in
runtestflags, otherwise we get an error '-mfloat-abi=soft and
-mfloat-abi=hard may not be used together' because we try to compile
with both flags.

2021-03-19  Christophe Lyon  <christophe.lyon@linaro.org>

	gcc/testsuite/
	* gcc.target/arm/armv8_1m-shift-imm-1.c: Remove -mfloat=abi option.
	* gcc.target/arm/armv8_1m-shift-reg-1.c: Likewise.
	* gcc.target/arm/bf16_dup.c: Likewise.
	* gcc.target/arm/bf16_reinterpret.c: Likewise.
	* gcc.target/arm/pr51534.c: Remove -mfloat=abi option.