spi_flash: add api to get valid mmu table pages number
See merge request idf/esp-idf!2070
(cherry picked from commit 8eaae96658)
75550315 add api get valid mmu table pages number
fa687743 spi_flash:
49a236da fix CI failed when flash chip size if 2MBytes
1) fixed SPI_read_status: added check for flash busy flag in matrix mode
2) fixed SPI_page_program: enable write before writing data to SPI FIFO
3) SPI flash ROM funcs replacement is controlled via menuconfig option
* App access functions are all flash encryption-aware
* Documentation for flash encryption
* Partition read/write is flash aware
* New encrypted write function