Input: i8042 - replace strlcat() with seq_buf and scnprintf()

In preparation for removing the strlcat() API[1], replace its uses in
i8042-acpipnpio.h.

i8042_pnp_id_to_string() accumulates a variable number of PNP ids in
a loop, which is what seq_buf is for. The kbd and aux probe functions
build a name from at most three parts that are all known up front, so
the whole construction becomes a single scnprintf() there.

Link: https://github.com/KSPP/linux/issues/370 [1]
Signed-off-by: Ian Bridges <icb@fastmail.org>
Link: https://patch.msgid.link/akyW4xkvCCROM0SE@dev
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>