Kernel: Add PCI::get_programming_interface(PCI::Address)

This returns the programming interface at a given PCI address.
This is sometimes referred to as "prog-if" on other systems.

Kernel/PCI/Access.cpp

@@ -193,6 +193,11 @@ u8 get_class(Address address)
     return read8(address, PCI_CLASS);
 }
 
+u8 get_programming_interface(Address address)
+{
+    return read8(address, PCI_PROG_IF);
+}
+
 u16 get_subsystem_id(Address address)
 {
     return read16(address, PCI_SUBSYSTEM_ID);

Kernel/PCI/Definitions.h

@@ -208,6 +208,7 @@ u32 get_BAR3(Address);
 u32 get_BAR4(Address);
 u32 get_BAR5(Address);
 u8 get_revision_id(Address);
+u8 get_programming_interface(Address);
 u8 get_subclass(Address);
 u8 get_class(Address);
 u16 get_subsystem_id(Address);