flash/stmqspi: minor fixes on coding style

Add space around operators;
use BIT() macro in place of left shifting constant 1;
remove space between cast operator and value;
do not check a pointer before free() it;
add parenthesis around parameters in macros;
fix indentation using only TABs;
remove line continuation '\' at code lines out of macros.

Change-Id: I809e8ee72d7bfe49d0edf10afb36efe2458de77c
Signed-off-by: Antonio Borneo <borneo.antonio@gmail.com>
Fixes: e44539d66c89 ("Flash, FRAM and EEPROM driver for STM32 QUAD-/OCTOSPI interface")
Reviewed-on: http://openocd.zylin.com/5932
Tested-by: jenkins
Reviewed-by: Christopher Head <chead@zaber.com>