The commit a28830b8

 aligned the data and rename some symbols.  However
there are two symbols at riscv linker script that were missing, which
causes below linker error:

kernel/xip.c:28: undefined reference to `__itcm_load_start'
kernel/xip.c:43: undefined reference to `__dtcm_data_load_start'

Rename below symbols to fix the issues.

__itcm_rom_start -> __itcm_load_start
__dtcm_data_rom_start -> __dtcm_data_load_start
Signed-off-by: Gerson Fernando Budke <nandojve@gmail.com>