[MTD] [NAND] nand_base.c: reset chip first

Some chips require a RESET after power-up (e.g. Micron MT29FxGxxxxx).
The first command sent is NAND_CMD_READID.
Issue a NAND_CMD_RESET in nand_scan_ident before reading the device id.
Tested with an MT29F4G08AAC.

Signed-off-by: Karl Beldan <karl.beldan@gmail.com>
Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>