mtd: nand: Use ULL-suffix for big u64 constant

drivers/mtd/nand/nand_timings.c:45: warning: integer constant is too large for ‘long’ type

[ Editorial note: This is a false warning. Looking at ISO draft N1124
    (this is approximately C11, the first PDF I had lying around),
    section 6.4.4.1 (statement 5):

       "The type of an integer constant is the first of the
        corresponding list in which its value can be represented."

    So this should not be an overflow, and any toolchain that says so
    (e.g., GCC 4.4) is buggy.

       -Brian ]

Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org>
Signed-off-by: Brian Norris <computersforpeace@gmail.com>