parport_pc: Remove stale `parport_pc_ecp_read_block_pio' reference

parport_pc: Remove stale `parport_pc_ecp_read_block_pio' reference

Complement commit 991214386dee ("parport: remove unused dead code from
lowlevel drivers") and remove a stale piece of commented-out code that
refers to a function removed with said commit.

Signed-off-by: Maciej W. Rozycki <macro@orcam.me.uk>
Signed-off-by: Sudip Mukherjee <sudipm.mukherjee@gmail.com>
Link: https://lore.kernel.org/r/20230108215656.6433-1-sudipm.mukherjee@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>