turnip: Remove unused TU_DEBUG_IR3 flag

Replaced by IR3_SHADER_DEBUG=disasm,{vs,...,cs} and unused since the
commit referenced below.

Fixes: 808992fc50 ("tu: Use the ir3 shader API")
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/8249>

src/freedreno/vulkan/tu_device.c

@@ -190,7 +190,6 @@ static const VkAllocationCallbacks default_alloc = {
 static const struct debug_control tu_debug_options[] = {
    { "startup", TU_DEBUG_STARTUP },
    { "nir", TU_DEBUG_NIR },
-   { "ir3", TU_DEBUG_IR3 },
    { "nobin", TU_DEBUG_NOBIN },
    { "sysmem", TU_DEBUG_SYSMEM },
    { "forcebin", TU_DEBUG_FORCEBIN },

src/freedreno/vulkan/tu_private.h

@@ -225,7 +225,6 @@ enum tu_debug_flags
 {
    TU_DEBUG_STARTUP = 1 << 0,
    TU_DEBUG_NIR = 1 << 1,
-   TU_DEBUG_IR3 = 1 << 2,
    TU_DEBUG_NOBIN = 1 << 3,
    TU_DEBUG_SYSMEM = 1 << 4,
    TU_DEBUG_FORCEBIN = 1 << 5,