fbtft: Fix the initialization from property algorithm

fbtft: Fix the initialization from property algorithm

When converting to device property API the commit
38fbe8f7ccaa ("fbtft: Make use of device property API")
mistakenly placed the reading of the first value inside the loop,
that jumps over value after initialization sequence or sleep commands.

Move the above mentioned reading outside of the loop to restore
correct behaviour.

Besides that, we are using pre-increment operation which may lead to
out of the boundary access at the end of sequence. Thus, allocate buffer
with an additional element at the end to prevent out of the boundary
access.

Fixes: 38fbe8f7ccaa ("fbtft: Make use of device property API")
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Link: https://lore.kernel.org/r/20191121140207.65089-1-andriy.shevchenko@linux.intel.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>