There is no need to store the result of the addition back to variable
consumed after the addition.  The store is redundant, replace += with just
+

Cleans up clang scan build warning: lib/ts_bm.c:83:11: warning: Although
the value stored to 'consumed' is used in the enclosing expression, the
value is never actually read from 'consumed' [deadcode.DeadStores]

Link: https://lkml.kernel.org/r/20220704215325.600993-1-colin.i.king@gmail.comSigned-off-by: Colin Ian King <colin.i.king@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>