tgafb: actually allocate memory for the pseudo_palette

No memory allocation was done for the pseudo_palette.  Allocate one for it.

Signed-off-by: Antonino Daplas <adaplas@gmail.com>
Acked-by: "Maciej W. Rozycki" <macro@linux-mips.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>