py/lexer: Remove unnecessary code, and unreachable code.

Setting emit_dent=0 is unnecessary because arriving in that part of the
if-logic will guarantee that emit_dent is already zero.

The block to check indent_top(lex)>0 is unreachable because a newline is
always inserted an the end of the input stream, and hence dedents are
always processed before EOF.
diff --git a/py/lexer.c b/py/lexer.c
index b2c9c5f..4a7c8f5 100644
--- a/py/lexer.c
+++ b/py/lexer.c
@@ -343,7 +343,6 @@
         lex->tok_kind = MP_TOKEN_NEWLINE;
 
         mp_uint_t num_spaces = lex->column - 1;
-        lex->emit_dent = 0;
         if (num_spaces == indent_top(lex)) {
         } else if (num_spaces > indent_top(lex)) {
             indent_push(lex, num_spaces);
@@ -359,16 +358,7 @@
         }
 
     } else if (is_end(lex)) {
-        if (indent_top(lex) > 0) {
-            lex->tok_kind = MP_TOKEN_NEWLINE;
-            lex->emit_dent = 0;
-            while (indent_top(lex) > 0) {
-                indent_pop(lex);
-                lex->emit_dent -= 1;
-            }
-        } else {
-            lex->tok_kind = MP_TOKEN_END;
-        }
+        lex->tok_kind = MP_TOKEN_END;
 
     } else if (is_char_or(lex, '\'', '\"')
                || (is_char_or3(lex, 'r', 'u', 'b') && is_char_following_or(lex, '\'', '\"'))