tools/nolibc: arm: use clang-compatible asm syntax

The clang assembler rejects the current syntax.
Switch to a syntax accepted by both GCC and clang.

Acked-by: Willy Tarreau <w@1wt.eu>
Link: https://lore.kernel.org/r/20240807-nolibc-llvm-v2-1-c20f2f5fc7c2@weissschuh.net
Signed-off-by: Thomas Weißschuh <linux@weissschuh.net>

Author: t-8ch

tools/include/nolibc/arch-arm.h

@@ -188,8 +188,8 @@
 void __attribute__((weak, noreturn, optimize("Os", "omit-frame-pointer"))) __no_stack_protector _start(void)
 {
 	__asm__ volatile (
-		"mov %r0, sp\n"         /* save stack pointer to %r0, as arg1 of _start_c */
-		"and ip, %r0, #-8\n"    /* sp must be 8-byte aligned in the callee        */
+		"mov r0, sp\n"          /* save stack pointer to %r0, as arg1 of _start_c */
+		"and ip, r0, #-8\n"     /* sp must be 8-byte aligned in the callee        */
 		"mov sp, ip\n"
 		"bl  _start_c\n"        /* transfer to c runtime                          */
 	);