Fix the warning for the file not end with newline

arm-linux-gnueabihf-as -o exit.o exit.arm.s

exit.arm.s: Assembler messages:
exit.arm.s: Warning: end of file not at end of a line; newline inserted

Signed-off-by: Dave Chen <dave.chen@arm.com>

util/binfmt_misc/fixtures/exit.amd64.s

@@ -3,4 +3,4 @@
 _start:
 	mov $60, %rax
 	xor %rdi, %rdi
-	syscall
+	syscall

util/binfmt_misc/fixtures/exit.arm.s

@@ -3,4 +3,4 @@
 _start:
 	mov %r0, $0x0
 	mov %r7, $0x01
-	swi 0x0
+	swi 0x0

util/binfmt_misc/fixtures/exit.arm64.s

@@ -3,4 +3,4 @@
 _start:
 	mov x0, #0
 	mov x8, #93
-	svc #0
+	svc #0