CI/travis/before_install_linux: remove fixed sleep
CI/travis/before_install_linux: remove fixed sleep

Was added out of paranoia initially (because the example that was used had
it), but it seems to work fine after removing it.

Signed-off-by: Alexandru Ardelean <685557f6b7c225d86b536740313ed51b24843a58@analog.com>

analogdevicesinc/libiio,analogdevicesinc/libiio,analogdevicesinc/libiio,analogdevicesinc/libiio