bootchooser: avoid write environment

[Stefano Manni]

Hi,

I'm using bootchooser to switch from a partition to another in case of
an update done in Linux userspace using the command bareboxenv.

But I see that at every boot the barebox decrements the number of
remaining attempts in the environment. 
I'd like to avoid continuing to write the env in order to preserve the
spinor flash memory.

Is there any already-ready mechanism to do it? 

Thanks all.
Best,
Stefano