LoongArch: Fix bitflag conflict for TIF_FIXADE

After LoongArch was converted to use the generic TIF bits in commit
f9629891 ("loongarch: Use generic TIF bits"), its TIF_FIXADE flag
takes the same bit with TIF_RESTORE_SIGMASK in thread_info.flags.

Such conflict causes TIF_FIXADE being considered cleared when
TIF_RESTORE_SIGMASK is cleared during deliver of a signal. And since
TIF_FIXADE determines whether unaligned access emulation works for a
task, userspace making use of unaligned access will receive unexpected
SIGBUS (and likely terminate) after receiving its first signal.

This conflict looks like a simple typo, switch it to the free bit 19.

Fixes: f9629891 ("loongarch: Use generic TIF bits")
Signed-off-by: Yao Zi <ziyao@disroot.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Wentao Guan <guanwentao@uniontech.com>