man: Fix omission of GBM
man: Fix omission of GBM

Replace the phrase with "X11/EGL and Wayland" with "EGL platforms".  Grep
reveals this to be the only omission.

Signed-off-by: Chad Versace <a557f7f75bf28dc19ac99107f5cc7cd6b3fbdb1a@linux.intel.com>

waffle-gl/waffle,evelikov/waffle,evelikov/waffle,maurossi/waffle,fjhenigman/waffle,yinquan529/waffle-gl-waffle,waffle-gl/waffle,janesma/waffle,yinquan529/waffle-gl-waffle,chadversary/waffle,janesma/waffle,fjhenigman/waffle,chadversary/waffle,dcbaker/waffle,dcbaker/waffle,maurossi/waffle,dcbaker/waffle,maurossi/waffle,fjhenigman/waffle,chadversary/waffle,waffle-gl/waffle,evelikov/waffle,yinquan529/waffle-gl-waffle,waffle-gl/waffle,janesma/waffle