efi_selftest: fix HII tests

efi_st_printf() does not support format code %ld. Anyway the format code
for size_t would be %zu which isn't supported either.

We do not want any divisions to avoid invalid references to integer
arithmetic routines, cf.
https://gcc.gnu.org/onlinedocs/gccint/Integer-library-routines.html

.

As a simple remedy remove the noisy messages from the output.
They are not relevant for automated testing.

Signed-off-by: Heinrich Schuchardt <xypron.glpk@gmx.de>
Signed-off-by: Alexander Graf <agraf@suse.de>