i3c: master: renesas: Fix memory leak in renesas_i3c_i3c_xfers()

i3c: master: renesas: Fix memory leak in renesas_i3c_i3c_xfers()

The xfer structure allocated by renesas_i3c_alloc_xfer() was never freed
in the renesas_i3c_i3c_xfers() function. Use the __free(kfree) cleanup
attribute to automatically free the memory when the variable goes out of
scope.

Fixes: d028219a9f14 ("i3c: master: Add basic driver for the Renesas I3C controller")
Tested-by: Tommaso Merciai <tommaso.merciai.xr@bp.renesas.com>
Reviewed-by: Tommaso Merciai <tommaso.merciai.xr@bp.renesas.com>
Reviewed-by: Frank Li <Frank.Li@nxp.com>
Signed-off-by: Felix Gu <ustc.gu@gmail.com>
Link: https://patch.msgid.link/20260406-renesas-v3-1-4b724d7708f4@gmail.com
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>