drm/ttm: Fix memory space allocation v2

In the event that TTM doesn't find a compatible memory type for the
driver's first placement choice (placement without eviction), TTM
returns -EINVAL without trying the driver's second choice.
This causes problems on vmwgfx when VRAM is disabled before first modeset
and during VT switches when fbdev is not enabled.

Fix this by also trying the driver's second choice before returning
-EINVAL.

v2: Also check that man->use_type is true for the driver's second choice.
Fixes a bug where disallowed memory types could be used.

Signed-off-by: Thomas Hellstrom <thellstrom@vmware.com>
Reviewed-by: Brian Paul <brianp@vmware.com>
Reviewed-by: Sinclair Yeh <syeh@vmware.com>