qcacld-3.0: Remove ol_get_fw_files() prototype
Change I2c217891d0ca4b503e7388b3ebe2f787e8325af5 ("qcacld-3.0: Add
firmware download support for sdio bus (Part 5 - HIF SDIO)") added a
prototype for ol_get_fw_files() but did not add an implementation.
Since nothing uses this prototype, remove it.
Change-Id: Ie3b9aee767e14acc425ca7c365d10cbb73682fb5
CRs-Fixed: 2366957