drm/vmwgfx: Fix memory allocation check and a leak of object fifo

The allocation of fifo is lacking an allocation failure check, so
fix this by adding one.

In the case where fifo->static_buffer fails to be allocated the
error return path neglects to kfree the fifo object. Fix this by
adding in the missing kfree.

Kudos to Dan Carpenter for spotting the missing kzalloc failure
check.

Addresses-Coverity: ("Resource leak")
Fixes: 2cd80dbd

 ("drm/vmwgfx: Add basic support for SVGA3")
Signed-off-by: Colin Ian King <colin.king@canonical.com>
Signed-off-by: Zack Rusin <zackr@vmware.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20210514144930.89813-1-colin.king@canonical.com