1st bootloader won't help to initialize the MSPI & cache properly as it
usually do when loading from flash. And the ram app doesn't have valid
headers.
Since there is no enough space in 2nd bootloader, we replace the
`bootloader_init_spi_flash` in the ram_app (!pure_ram_app), with an
customized alternative of it for the ram_app.
This alternative helps to initialize the MSPI & cache properly, without
the help of 1st bootloader or image headers.
