staging:rtl8192u: Rename EEPROM_TxPwIndex_CCK - Style

Rename the constant EEPROM_TxPwIndex_CCK to EEPROM_TX_PW_INDEX_CCK.
This change clears the checkpatch issue with CamelCase naming.

The change is coding style in nature so should have no impact on
runtime code execution.

Signed-off-by: John Whitmore <johnfwhitmore@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>