staging: sm750fb: fix CamelCase function parameter

Change function parameter in header file from powerMode to mode,
now identical to c file function declaration. Issue found by checkpatch.
Signed-off-by: Arne Petersen <petersenarne@yahoo.com>
Link: https://lore.kernel.org/r/Yq2NufHtWbuXCjWE@ubuntuSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/sm750fb/ddk750_power.h

@@ -15,7 +15,7 @@ enum dpms {
 }
 
 void ddk750_set_dpms(enum dpms state);
-void sm750_set_power_mode(unsigned int powerMode);
+void sm750_set_power_mode(unsigned int mode);
 void sm750_set_current_gate(unsigned int gate);
 
 /*