common: board: make initcalls static

common: board: make initcalls static

Change board_init_f(), board_init_f_r() and board_init_r() to make
static calls instead of iterating over the init_sequence_f,
init_sequence_f_r and init_sequence_r arrays, respectively. This makes
the code a simpler (and even more so when initcall_run_list() is
later removed) and it reduces the binary size as well. Tested with
xilinx_zynqmp_kria_defconfig; bloat-o-meter results:

- With LTO
add/remove: 106/196 grow/shrink: 10/28 up/down: 31548/-33829 (-2281)
Total: Before=1070471, After=1068190, chg -0.21%
- Without LTO
add/remove: 0/54 grow/shrink: 3/0 up/down: 2322/-2832 (-510)
Total: Before=1121723, After=1121213, chg -0.05%

Execution time does not change in a noticeable way.

Signed-off-by: Jerome Forissier <jerome.forissier@linaro.org>