Remove redundant prototype declaration

[kevinpt]

USBD_CDC_GetOtherSpeedCfgDesc() already declared on line 111

IMPORTANT INFORMATION

Contributor License Agreement (CLA)

• The Pull Request feature will be considered by STMicroelectronics after the signature of a Contributor License Agreement (CLA) by the submitter.
• If you did not sign such agreement, please follow the steps mentioned in the CONTRIBUTING.md file.

[ASELSTM]

ST Internal Reference: 129894