riscv: dts: spacemit: add i2c aliases on BPI-F3

riscv: dts: spacemit: add i2c aliases on BPI-F3

Add i2c aliases for i2c2 and i2c8 on BPI-F3. This is useful to keep a
stable number for the /dev entries after loading the i2c-dev module.

Signed-off-by: Aurelien Jarno <aurelien@aurel32.net>
Reviewed-by: Troy Mitchell <troy.mitchell@linux.spacemit.com>
Reviewed-by: Vivian Wang <wangruikang@iscas.ac.cn>
Reviewed-by: Yixun Lan <dlan@gentoo.org>
Link: https://lore.kernel.org/r/20250926175833.3048516-4-aurelien@aurel32.net
Signed-off-by: Yixun Lan <dlan@gentoo.org>