conf/machine/hx4700.conf: do not set IMAGE_FSTYPES
conf/machine/hx4700.conf: do not set IMAGE_FSTYPES

No other machine sets this; rely on the default for now.

Signed-off-by: Paul Eggleton <737d4dae46a541673d7bf4e0d5b32714b16528d8@linux.intel.com>

bluelightning/meta-handheld,bluelightning/meta-handheld