x86/edison: Speed up mraa_gpio_dir

Reasonable speed up in the mraa_gpio_dir on the Edison Arduino board
x86/galileo-gen2: Speed up mraa_gpio_dir

Made like changes to Edison to cache the output enable
Still testing.

Note: different than Edison as the pin structure holds enable pin number
instead of external array.

2nd note: noticed PU resistors are also in structure but there is also
external array.

Signed-off-by: Kurt Eckhardt <kurte@rockisland.com>