bootloader: make GCLK_GEN_0 and GCLK_GEN_3 run in standby

Signed-off-by: Adam Wujek <dev_public@wujek.eu>
Status Job ID Name Coverage
  Build Fw
passed #9544
arm-clang-coast
make_bootloader_fw

00:11

passed #9543
arm-clang-coast
make_main_fw

00:15

passed #9545
arm-clang-coast
make_test_master_fw

00:15