i3c: prefix hexadecimal entries in sysfs

Hexadecimal values in sysfs should be prefixed with '0x' like e.g. PCI
and SCSI already do it. Also ensure the two digit length since BCR and
DCR are a byte in size.

Signed-off-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
Reviewed-by: Frank Li <Frank.Li@nxp.com>
Link: https://lore.kernel.org/r/20250707115409.73545-2-wsa+renesas@sang-engineering.com


Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>