[PATCH] device property: Make modifications of fwnode "flags" thread safe

[Wolfram Sang]

> > ... this change costs some memory on every system. Maybe it can be
> > avoided?
> 
> How much memory does it cost? On most 64-bit architectures is +4 bytes,
> rarely +0 bytes, on m68k it might be +2bytes. On 32-bit it most likely
> +0 bytes. I expect that 64-bit machines will cope with this bump.

I am not opposing that the issue should be fixed. If it is not possible
to take the lock everywhere, this is a proper solution. But if we don't
have to use more memory, then we could save it. Our new SoC easily has
'struct device' in the hundreds.