BUG/MINOR: mux-h2: Fix H2_CF_DEM_SHORT_READ value

BUG/MINOR: mux-h2: Fix H2_CF_DEM_SHORT_READ value

The value for H2_CF_DEM_SHORT_READ flag is wrong. 2 bits are erroneously
set, 0x200 and 0x80000.  It is not an issue because both bits are not used
anywhere else.

The typo was introduced in the commit b5f7b5296 ("BUG/MEDIUM: mux-h2: Handle
remaining read0 cases on partial frames"). Thus this patch must also be
backported as far a 2.0.

(cherry picked from commit 47940c39e2195f03960a461081488c7603ad7167)
Signed-off-by: Christopher Faulet <cfaulet@haproxy.com>
(cherry picked from commit 484f10ad3bd735cd729b60b988a73e6f0c4dd391)
Signed-off-by: Christopher Faulet <cfaulet@haproxy.com>