The board_r init function was complaining that we are looping through
an array, calling all our tiny init stubs sequentially via indirect
function calls (which can't be speculated, so they are slow).

The solution to that is pretty easy though. All we need to do is inline
the function that loops through the functions and the compiler will
automatically convert almost all indirect calls into direct inlined code.

With this patch, the overall code size drops (by 40 bytes on riscv64)
and boot time should become measurably faster for every target.
Signed-off-by: NAlexander Graf <agraf@suse.de>