net/pppoe: fix a typo for the PPPOE_HASH_BITS_1 definition

net/pppoe: fix a typo for the PPPOE_HASH_BITS_1 definition

Instead of its intention to define PPPOE_HASH_BITS_1, commit 96ba44c637b0
("net/pppoe: make number of hash bits configurable") actually defined
config PPPOE_HASH_BITS_2 twice in the ppp's Kconfig file due to a quick
typo with the numbers.

Fix the typo and define PPPOE_HASH_BITS_1.

Fixes: 96ba44c637b0 ("net/pppoe: make number of hash bits configurable")
Signed-off-by: Lukas Bulwahn <lukas.bulwahn@gmail.com>
Reviewed-by: Simon Horman <simon.horman@corigine.com>
Reviewed-by: Jaco Kroon <jaco@uls.co.za>
Link: https://lore.kernel.org/r/20230605072743.11247-1-lukas.bulwahn@gmail.com
Signed-off-by: Paolo Abeni <pabeni@redhat.com>