kselftest/arm64: Remove redundant _start labels from FP tests

There are a number of freestanding static executables used in floating
point testing that have no runtime at all. These all define the main entry
point as:

   .globl _start
   function _start
   _start:

but clang's integrated assembler complains that:

  error: symbol '_start' is already defined

due to having both a label and function directive. Remove the label to
allow building with clang.

No functional change.

Signed-off-by: Mark Brown <broonie@kernel.org>
Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>
Link: https://lore.kernel.org/r/20230111-arm64-kselftest-clang-v1-2-89c69d377727@kernel.org
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>

tools/testing/selftests/arm64/fp/fp-pidbench.S

@@ -31,7 +31,6 @@
 // Main program entry point
 .globl _start
 function _start
-_start:
 	puts	"Iterations per test: "
 	mov	x20, #10000
 	lsl	x20, x20, #8

tools/testing/selftests/arm64/fp/fpsimd-test.S

@@ -215,7 +215,6 @@ endfunction
 // Main program entry point
 .globl _start
 function _start
-_start:
 	mov	x23, #0		// signal count
 
 	mov	w0, #SIGINT

tools/testing/selftests/arm64/fp/sve-test.S

@@ -378,7 +378,6 @@ endfunction
 // Main program entry point
 .globl _start
 function _start
-_start:
 	mov	x23, #0		// Irritation signal count
 
 	mov	w0, #SIGINT

tools/testing/selftests/arm64/fp/za-test.S

@@ -231,7 +231,6 @@ endfunction
 // Main program entry point
 .globl _start
 function _start
-_start:
 	mov	x23, #0		// signal count
 
 	mov	w0, #SIGINT