This is to prevent a compile error caused by function prototype conflict between a function called `select()` (present in a number of sensortag peripheral drivers) and the one in `sys/select.h`. The error manifests itself with gcc-arm-embedded version 5.2.1 20151202 (2015-q4).
To fix the error we simply rename our function.
Fixes#1434
For the SPI
* We improve the return semantics of _read() and _write()
* We set speed based on the value returned from ti_lib_sys_ctrl_clock_get() instead of using a hard-coded value
External flash changes:
* Rename macros to match instruction names
* verify_part(): Return a different value when the device is powered down and when communication fails
* Change return value semantics of static functions
* Adjust checks of board_spi_ return values
* Wait for BUSY to clear before attempting to send PD
* Accept two possible flash parts: W25X40CL (4MBit) as well as the W25X20CL (2MBit)
* Explicitly put in deep sleep on device startup
* Verify that the flash has actually dropped to deep sleep
* Update CLK pin to match the one used on the v1.2 sensortag
Obsoletes and Closes#988