Fix: Garbage at higher bytes of IRR, ISR

Author: coderarjob

include/x86/io.h

@@ -17,7 +17,7 @@
 #include <types.h>
 
 #define outb(p,v) __asm__ volatile ("out dx, al;" : :"a" (v), "d" (p))
-#define inb(p,v)  __asm__ volatile ("in al, dx" :"=a" (v) :"d" (p))
+#define inb(p,v)  __asm__ volatile ("xor %0, %0; in al, dx" :"=a" (v) :"d" (p))
 // Reference: https://wiki.osdev.org/Inline_Assembly/Examples#IO_WAIT
 #define io_delay() outb(0x80, 0)