tools/nolibc: move the call to __sysret() into syscall()

tools/nolibc: move the call to __sysret() into syscall()

__sysret() transforms the return value from the kernel into the libc
return value convention. There is no reason for it to be called in the
middle of the internals of the syscall() implementation macros.

Move the call up, directly into syscall(), to make the code simpler.

Signed-off-by: Thomas Weißschuh <linux@weissschuh.net>
Acked-by: Willy Tarreau <w@1wt.eu>
Link: https://patch.msgid.link/20260405-nolibc-syscall-v1-2-e5b12bc63211@weissschuh.net