embassy-boot: remove default features from embassy-embedded-hal

[tomasbarton-stemcell]

embassy-embedded-hal enables the time feature by default, which will require you to include the time driver if you use any of the functions that use it (for example spi::blocking::transaction), otherwise the binary fails to link.

[Dirbaio]

I'd prefer to make the time feature not default. Default features are a footgun precisely because this reason, too easy to forgot to disable them.