arm64: Remove unused VGA console support

Support for VGA_CONSOLE is not allowable due to commit ee23794b
("video: vgacon: Don't build on arm64"), thus remove the associated
unused code.

Whilst PCI on arm64 would support VGA a valid screen_info structure
is missing.
Acked-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Andrew Murray <andrew.murray@arm.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>

arch/arm64/kernel/setup.c

@@ -351,11 +351,7 @@ void __init setup_arch(char **cmdline_p)
 #endif
 
 #ifdef CONFIG_VT
-#if defined(CONFIG_VGA_CONSOLE)
-	conswitchp = &vga_con;
-#elif defined(CONFIG_DUMMY_CONSOLE)
 	conswitchp = &dummy_con;
-#endif
 #endif
 	if (boot_args[1] || boot_args[2] || boot_args[3]) {
 		pr_err("WARNING: x1-x3 nonzero in violation of boot protocol:\n"