i3c: Fix MODALIAS uevents

file2alias uses %X formatters. Fix typos in the MODALIAS uevent to print
the part and ext IDs in uppercase.

Signed-off-by: Boris Brezillon <boris.brezillon@collabora.com>
Signed-off-by: Vitor Soares <vitor.soares@synopsys.com>
Link: https://lore.kernel.org/linux-i3c/9ac5f1f8413fbb0481de76b5e43f2f4e1b2dc49f.1582796652.git.vitor.soares@synopsys.com