mtd: cfi: Fix checking status register feature

Commit 72443c7f ("mtd: cfi: Add support for status register
polling") added a feature check to determine if status register
is available for certain flash chips. The "lower software bits"
register used to determine this feature is not backward compati-
ble. Older flash chips without this feature has reserved value
0xff. Instead of checking "lower software bits" register, use
CFI primary vendor-specific extended query. Since CFI version
1.4, software features can be read from offset 0x53 according to
document AN201168 from Cypress.

Signed-off-by: York Sun <york.sun@nxp.com>
CC: Marek Vasut <marek.vasut@gmail.com>
Tested-by: Marek Vasut <marek.vasut@gmail.com>
Signed-off-by: Stefan Roese <sr@denx.de>