usrp: Add set_gpio_attr overload that use string

 1/ multi_usrp.hpp; multi_usrp.cpp: added new functions
       - set_gpio_attr() that allow user to set certain attribute by string
         value.
       - get_gpio_string_attr() return string type value of certain attribute.
 2/ gpio_defs.hpp; gpio_atr_3000.cpp : added new definition of SRC attribute.
 This commit enable user to use multi_usrp api to set_gpio_attr using string
value. This is helpful; because the attribute can represent more than two state
as of old API. This enable user to set SRC (source) that drive each GPIO bank's
pin. Source can be either processing unit(PS) or radio frontend logic from FPGA
logic.

0 files changed, 0 insertions, 0 deletions