ath9k: remove unnecessary code

ath9k: remove unnecessary code

The array field eeprom_data in struct th9k_platform_data
is a fixed size array so it can never be NULL.

Addresses-Coverity-ID: 1364903
Cc: Arend Van Spriel <arend.vanspriel@broadcom.com>
Cc: Kalle Valo <kvalo@qca.qualcomm.com>
Signed-off-by: Gustavo A. R. Silva <garsilva@embeddedor.com>
Signed-off-by: Kalle Valo <kvalo@qca.qualcomm.com>
[sw0312.kim: backport upstream commit 641c1f4ab7f6 to resolve gcc-12 build issue]
Signed-off-by: Seung-Woo Kim <sw0312.kim@samsung.com>
Change-Id: I22a7282d73ac13f190fe8acc0b433abed128d71d