Remove unused static functions

IAR generates warning Pe177 'function was declared but never referenced'.

spi/max7219_32x8_spi/max7219_32x8_spi.c

@@ -55,15 +55,6 @@ static inline void cs_deselect() {
 #endif
 
 #if defined(spi_default) && defined(PICO_DEFAULT_SPI_CSN_PIN)
-static void write_register(uint8_t reg, uint8_t data) {
-    uint8_t buf[2];
-    buf[0] = reg;
-    buf[1] = data;
-    cs_select();
-    spi_write_blocking(spi_default, buf, 2);
-    cs_deselect();
-    sleep_ms(1);
-}
 
 static void write_register_all(uint8_t reg, uint8_t data) {
     uint8_t buf[2];

spi/max7219_8x7seg_spi/max7219_8x7seg_spi.c

@@ -55,16 +55,6 @@ static inline void cs_deselect() {
 #endif
 
 #if defined(spi_default) && defined(PICO_DEFAULT_SPI_CSN_PIN)
-static void write_register(uint8_t reg, uint8_t data) {
-    uint8_t buf[2];
-    buf[0] = reg;
-    buf[1] = data;
-    cs_select();
-    spi_write_blocking(spi_default, buf, 2);
-    cs_deselect();
-    sleep_ms(1);
-}
-
 static void write_register_all(uint8_t reg, uint8_t data) {
     uint8_t buf[2];
     buf[0] = reg;

timer/timer_lowlevel/timer_lowlevel.c

@@ -9,18 +9,6 @@
 #include "hardware/timer.h"
 #include "hardware/irq.h"
 
-/// \tag::get_time[]
-// Simplest form of getting 64 bit time from the timer.
-// It isn't safe when called from 2 cores because of the latching
-// so isn't implemented this way in the sdk
-static uint64_t get_time(void) {
-    // Reading low latches the high value
-    uint32_t lo = timer_hw->timelr;
-    uint32_t hi = timer_hw->timehr;
-    return ((uint64_t) hi << 32u) | lo;
-}
-/// \end::get_time[]
-
 /// \tag::alarm_standalone[]
 // Use alarm 0
 #define ALARM_NUM 0