mt76: mt7615: support loading EEPROM for MT7613BE

EEPROM blobs for MT7613BE radios start with (little endian) 0x7663,
which is also the PCI device ID for this device. The EEPROM is required
for the radio to work at useful power levels, otherwise only the lowest
power level is available.

Suggested-by: Georgi Vlaev <georgi.vlaev@konsulko.com>
Tested-by: Stijn Segers <foss@volatilesystems.org>
Signed-off-by: Sander Vanheule <sander@svanheule.net>
Signed-off-by: Felix Fietkau <nbd@nbd.name>