nrf: Add more math sources to Makefile, and enable log2 implementation.

This commit adds a few math functions to the source list in the Makefile,
and implements the log2f function, so that ulab can be compiled on the nrf
boards.  It also addresses part of #5162.

ports/nrf/Makefile

@@ -160,8 +160,16 @@ SRC_LIB += $(addprefix lib/,\
         libm/sf_modf.c \
         libm/sf_ldexp.c \
         libm/asinfacosf.c \
+        libm/acoshf.c \
+        libm/asinhf.c \
         libm/atanf.c \
         libm/atan2f.c \
+        libm/atanhf.c \
+        libm/log1pf.c \
+        libm/sf_erf.c \
+        libm/erf_lgamma.c \
+        libm/wf_lgamma.c \
+        libm/wf_tgamma.c \
         libm/roundf.c \
 	)
 
@@ -186,8 +194,17 @@ SRC_LIB += $(addprefix lib/,\
         libm/sf_modf.c \
         libm/sf_ldexp.c \
         libm/asinfacosf.c \
+        libm/acoshf.c \
+        libm/asinhf.c \
         libm/atanf.c \
         libm/atan2f.c \
+        libm/atanhf.c \
+        libm/log1pf.c \
+        libm/sf_erf.c \
+        libm/erf_lgamma.c \
+        libm/wf_lgamma.c \
+        libm/wf_tgamma.c \
+        libm/roundf.c \
         )
 
 SRC_NRFX += $(addprefix lib/nrfx/drivers/src/,\

ports/nrf/mpconfigport.h

@@ -330,3 +330,7 @@ extern const struct _mp_obj_module_t ble_module;
 #include <alloca.h>
 
 #define MICROPY_PIN_DEFS_PORT_H "pin_defs_nrf5.h"
+
+#ifndef MP_NEED_LOG2
+#define MP_NEED_LOG2                (1)
+#endif