am335x_hs_evm: Trim options in SPL to reduce binary size

The am335x_hs_evm runs into size constraint problems at times with
various toolchains as changes come in due to the config have a large
number of options in SPL (to showcase what is possible) while also
having rather constrained binary limits.  Gain some of this room back by
lowering the loglevel, disabling HW partition support and switching over
to the tiny FIT image support.

Cc: Andrew F. Davis <afd@ti.com>
Signed-off-by: Tom Rini <trini@konsulko.com>
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I'd really appreciate a run-time test of this patch if at all possible
as I'm a little worried about TINY_FIT being incompatible with all of
the security options.  Thanks!