Use etshal.h from more recent micropython.

[schinckel]

This is a straight copy of the file from the master of micropython.

I'm not sure if the defines at the start should be changed or not.

[jedie]

Yes, it fixed this:

xtensa-lx106-elf-gcc -O0 -I. -mlongcalls -ffunction-sections -fdata-sections   -c -o boot8266.o boot8266.c
In file included from boot8266.c:32:0:
etshal.h:16:6: error: conflicting types for 'uart_div_modify'
 void uart_div_modify();
      ^
etshal.h:16:1: note: an argument type that has a default promotion can't match an empty parameter name list declaration
 void uart_div_modify();
 ^
In file included from boot8266.c:29:0:
/opt/xtensa-lx106-elf/xtensa-lx106-elf/sysroot/usr/include/user_interface.h:652:6: note: previous declaration of 'uart_div_modify' was here
 void uart_div_modify(uint8 uart_no, uint32 DivLatchValue);
      ^
<builtin>: recipe for target 'boot8266.o' failed
make[1]: *** [boot8266.o] Error 1

isn't it?