nimble/hw: Fix compilation of nrf51 driver
nimble/hw: Fix compilation of nrf51 driver

Compiling repos/apache-mynewt-nimble/nimble/drivers/nrf51/src/ble_hw.c
Error: repos/apache-mynewt-nimble/nimble/drivers/nrf51/src/ble_hw.c: In function 'ble_hw_get_public_addr':
repos/apache-mynewt-nimble/nimble/drivers/nrf51/src/ble_hw.c:69:23: error: passing argument 2 of 'memcpy'
     discards 'volatile' qualifier from pointer target type [-Werror=discarded-qualifiers]
     memcpy(addr->val, &NRF_FICR->DEVICEADDR[0], 4);
                       ^
In file included from repos/apache-mynewt-nimble/nimble/drivers/nrf51/src/ble_hw.c:22:0:
repos/apache-mynewt-core/libc/baselibc/include/string.h:19:16: note: expected 'const void *' but argument is
     of type 'const volatile uint32_t * {aka const volatile long unsigned int *}'
 __extern void *memcpy(void *, const void *, size_t);
                ^~~~~~
repos/apache-mynewt-nimble/nimble/drivers/nrf51/src/ble_hw.c:70:27: error: passing argument 2 of 'memcpy'
     discards 'volatile' qualifier from pointer target type [-Werror=discarded-qualifiers]
     memcpy(&addr->val[4], &NRF_FICR->DEVICEADDR[1], 2);
                           ^
In file included from repos/apache-mynewt-nimble/nimble/drivers/nrf51/src/ble_hw.c:22:0:
repos/apache-mynewt-core/libc/baselibc/include/string.h:19:16: note: expected 'const void *' but argument is
     of type 'const volatile uint32_t * {aka const volatile long unsigned int *}'
 __extern void *memcpy(void *, const void *, size_t);
                ^~~~~~

apache/mynewt-nimble,apache/mynewt-nimble,apache/mynewt-nimble,apache/mynewt-nimble,apache/mynewt-nimble