wifi: ath5k: Remove redundant dev_err()

There is no need to call the dev_err() function directly to print a custom
message when handling an error from platform_get_irq() function as it is
going to display an appropriate error message in case of a failure.

Signed-off-by: Ruan Jinjie <ruanjinjie@huawei.com>
Signed-off-by: Kalle Valo <quic_kvalo@quicinc.com>
Link: https://lore.kernel.org/r/20230726171235.2475625-1-ruanjinjie@huawei.com