DISCO_F413ZH : set default Wifi module SPI state to inactive

[jeromecoutant]

Description

In DISCO_F413ZH board, Arduino connector and Wifi embeded module are sharing the same SPI pins.

We need to set the default SPI SS pin for the Wifi module to the inactive state i.e. 1

See board User Manual: WIFI_SPI_CS = PG_11

PS: maybe there is a cleaner way with MBED to set some default GPIO state ?

Test

SPI test with CI shield was failed before.

target	platform_name	test suite	result	elapsed_time (sec)	copy_method
DISCO_F413ZH-ARM	DISCO_F413ZH	tests-api-spi	OK	18.41	default

@screamerbg

Pull request type

[x] Fix
[ ] Refactor
[ ] Target update
[ ] Functionality change
[ ] Breaking change