types: drop definition of __EXPORTED_HEADERS__

types: drop definition of __EXPORTED_HEADERS__

This definition disarms the warning in uapi/linux/types.h about including
kernel headers from user space.  However the warning is already disarmed
due to the fact that kernel code is built with -D__KERNEL__.

Drop the pointless definition.

Link: https://lkml.kernel.org/r/20251230-exported-headers-types-h-v1-1-947fc606f3d8@linutronix.de
Signed-off-by: Thomas Weißschuh <thomas.weissschuh@linutronix.de>
Cc: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>