riscv: mbv: Moving little_endian variable to data section

riscv: mbv: Moving little_endian variable to data section

SPL is cleaning bss after calling board_init_f. Setting up console is done
and little_endian global variable is cleared which caused that console
stops to work. That's why move it to data seciton now. The patch should be
reverted when bss is cleared before board_init_f is called.

Signed-off-by: Michal Simek <michal.simek@amd.com>
Link: https://lore.kernel.org/r/934dc8871c59265eb9d8012193aa97d9b8bd7f33.1707911544.git.michal.simek@amd.com