staging:rtl8192u: Rename eRFPath - Style

Rename the variable eRFPath to e_rfpath. This change resolves a
checkpatch issue with CamelCase naming. The variable name is used both
as a parameter name in function definitions, function prototypes and as
a local variable.

This change is purely a coding style change which 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>