ipq8074: add Netgear RBK750 BDF

For use in Netgear RBR750 and RBS750.

Extracted from GPL sources of firmware version 7.2.8.5:

package/base-files/files/lib/firmware/IPQ8074/bdwlan.b213

The file is identical with the ones under the ETSI, FCC, HKG, IND, SGP
and VNM subdirectories.

ath11k-bdencoder -i board-netgear_rbk750.ipq8074
FileSize: 131180
FileCRC32: cb24c6c0
FileMD5: 31172df8a51d089d6d489610d6ec49cd
BoardNames[0]: 'bus=ahb,qmi-chip-id=0,qmi-board-id=255,variant=Netgear-RBK750'
BoardLength[0]: 131072
BoardCRC32[0]: 576c9fef
BoardMD5[0]: 03182c0c961df0a54784d9913a4633fa

Signed-off-by: Michael Lotz <mmlr@mlotz.ch>
Link: #126
Signed-off-by: Robert Marko <robimarko@gmail.com>

Author: mmlr