Fix off by 1 error

i can increment > qs_kv_size with some inputs. Fix this
by incrementing earlier in the loop instead so we don't
have to increment after the loop and possibly go past
max.

Tested: Used bad string and no longer saw segfault

Change-Id: Ia68cd9b24e9a0b16646197983c513d78df2239ed
Signed-off-by: James Feist <james.feist@linux.intel.com>