esp8266/etshal.h: Remove unneeded function declarations.

These removed ones are either unused by MicroPython or provided by osapi.h
in the SDK.  In particular ets_delay_us() has different signatures for
different versions of the SDK, so best to let it provide the declaration.

Fixes issue #8095.

Signed-off-by: Damien George <damien@micropython.org>

ports/esp8266/etshal.h

@@ -6,22 +6,10 @@
 // see http://esp8266-re.foogod.com/wiki/Random_Number_Generator
 #define WDEV_HWRNG ((volatile uint32_t *)0x3ff20e44)
 
-void ets_delay_us(uint16_t us);
-void ets_intr_lock(void);
-void ets_intr_unlock(void);
 void ets_isr_mask(uint32_t mask);
 void ets_isr_unmask(uint32_t mask);
-void ets_isr_attach(int irq_no, void (*handler)(void *), void *arg);
-void ets_install_putc1();
-void uart_div_modify(uint8_t uart, uint32_t divisor);
-void ets_set_idle_cb(void (*handler)(void *), void *arg);
 
-void ets_timer_arm_new(os_timer_t *tim, uint32_t millis, bool repeat, bool is_milli_timer);
-void ets_timer_setfn(os_timer_t *tim, ETSTimerFunc callback, void *cb_data);
-void ets_timer_disarm(os_timer_t *tim);
-
-extern void ets_wdt_disable(void);
-extern void wdt_feed(void);
+void ets_wdt_disable(void);
 
 // Opaque structure
 #ifndef MD5_CTX
@@ -32,12 +20,6 @@ void MD5Init(MD5_CTX *context);
 void MD5Update(MD5_CTX *context, const void *data, unsigned int len);
 void MD5Final(unsigned char digest[16], MD5_CTX *context);
 
-// These prototypes are for recent SDKs with "malloc tracking"
-void *pvPortMalloc(size_t sz, const char *fname, unsigned line);
-void *pvPortZalloc(size_t sz, const char *fname, unsigned line);
-void *pvPortRealloc(void *p, unsigned sz, const char *fname, unsigned line);
-void vPortFree(void *p, const char *fname, unsigned line);
-
 uint32_t SPIRead(uint32_t offset, void *buf, uint32_t len);
 uint32_t SPIWrite(uint32_t offset, const void *buf, uint32_t len);
 uint32_t SPIEraseSector(int sector);