gpu: ion: Remove heapmask from client

The heapmask in the client generally wasn't being used.  This
patch removes it.

Change-Id: I18bcf11089a0bc20373327ffaead41f73e810e78
Signed-off-by: Rebecca Schultz Zavin <rebecca@android.com>
Git-commit: cd56ef058fdf8aed9cf583e25c6e20308cd61521
Git-repo: https://android.googlesource.com/kernel/common


[lauraa@codeaurora.org: Dropped debugfs changes, adjusted
msm_ion_client_create for compilation purposes]
Signed-off-by: Laura Abbott <lauraa@codeaurora.org>