tests: drivers: i2c: Fix incorrect file paths in SCI I2C test support

The current paths to the .overlay and .conf files used for SCI I2C tests
are incorrect, as they include {NORMALIZED_BOARD_QUALIFIERS}, which does
not exist in the actual file names.

This commit corrects the file paths in the test support configuration.

Signed-off-by: Khoa Tran <khoa.tran.yj@bp.renesas.com>