Fix QSPI parameter error on erase command
Fix QSPI parameter error on erase command

According to NRF52840 PS, the erase operation on QSPI only accepts 4k,
64kb or all memory as parameters, which are encoded in the 2 LSb
(QSPI 52.10.12). This makes the erase command call 4KB erase for each
sector inside the user defined `QSPI_FLASH_SECTOR_SIZE`.

Signed-off-by: Fabio Utzig <66676b1ceaf93296e098708c09494361103aa635@apache.org>

mlaz/mynewt-core,mlaz/mynewt-core,mlaz/mynewt-core,mlaz/mynewt-core,mlaz/mynewt-core