env: clean environment.h checkpatch and code style

Though one warning left:
 WARNING: do not add new typedefs
 #149: FILE: u-boot/include/environment.h:149:
 +typedef struct environment_s {

 total: 0 errors, 1 warnings, 181 lines checked

Signed-off-by: Igor Grinberg <grinberg@compulab.co.il>
1 file changed