mtd: denali: use 8 bytes for READID command

The Denali NAND driver reads only 5 bytes of ID, but some Hynix and Samsung
have size parameters in the 6th byte.  As a result, the page and oob size
for a Hynix H27UAG8T2B were calculated incorrectly and the driver failed to
load.

The solution is to read 8 bytes of ID, as expected by the NAND framework.

Signed-off-by: Graham Moore <grmoore@altera.com>
Signed-off-by: Brian Norris <computersforpeace@gmail.com>