bng_en: update module description

bng_en: update module description

The Broadcom BCM57708/800G NIC family is branded as ThorUltra.
Update the driver description accordingly.

Fixes: 74715c4ab0fa0 ("bng_en: Add PCI interface")
Signed-off-by: Rajashekar Hudumula <rajashekar.hudumula@broadcom.com>
Reviewed-by: Vikas Gupta <vikas.gupta@broadcom.com>
Reviewed-by: Bhargava Chenna Marreddy <bhargava.marreddy@broadcom.com>
Link: https://patch.msgid.link/20251217104748.3004706-1-rajashekar.hudumula@broadcom.com
Signed-off-by: Paolo Abeni <pabeni@redhat.com>