mtd: nand: make Samsung SLC NAND usable again

mtd: nand: make Samsung SLC NAND usable again

commit c51d0ac59f24 ("mtd: nand: Move Samsung specific init/detection
logic in nand_samsung.c") introduced a regression for Samsung SLC NAND
chips. Prior to this commit chip->bits_per_cell was initialized by calling
nand_get_bits_per_cell() before interpreting the ID bytes retrieved
from the chip. With the offending commit this call is skipped, leaving
chip->bits_per_cell cleared to zero when the manufacturer specific
'.detect' function is called. This is interpreted by nand_is_slc() as
an indicator for an MLC chip (bits_per_cell != 1).
The effect is that e.g. a K9F1G08U0F NAND chip is falsely detected as
MLC NAND with 4KiB page size rather than SLC with 2KiB page size.

Add a call to nand_get_bits_per_cell() before calling the .detect hook
function in nand_manufacturer_detect(), so that the nand_is_slc()
calls in the manufacturer specific code will return correct results.