gitignore: drop some useless entries

Some version.h files had been removed in commit 4627cd4:
[ HV: build: drop useless files ]

drop the remaining references in .gitignore as well.

Also drop hypervisor/build and devicemodel/build, they are redundant
since the pattern 'build' exists.

Tracked-On: #1599
Signed-off-by: Ming Liu <liu.ming50@gmail.com>

Author: liuming50

.gitignore

@@ -1,7 +1,3 @@
-hypervisor/build/
-hypervisor/bsp/uefi/include/bsp/version.h
-hypervisor/bsp/sbl/include/bsp/version.h
-devicemodel/build/
 devicemodel/include/version.h
 doc/doxygen
 doc/_build