x86/kexec: Remove spurious unconditional JMP from from identity_mapped()

This seemingly straightforward JMP was introduced in the initial version
of the the 64bit kexec code without any explanation.

It turns out (check accompanying Link) it's likely a copy/paste artefact
from 32-bit code, where such a JMP could be used as a serializing
instruction for the 486's prefetch queue. On x86_64 that's not needed
because there's already a preceding write to cr4 which itself is
a serializing operation.

  [ bp: Typos. Let's try this and see what cries out. If it does,
    reverting it is trivial. ]
Signed-off-by: Nikolay Borisov <nik.borisov@suse.com>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Link: https://lore.kernel.org/all/55bc0649-c017-49ab-905d-212f140a403f@citrix.com/

arch/x86/kernel/relocate_kernel_64.S

@@ -153,9 +153,6 @@ SYM_CODE_START_LOCAL_NOALIGN(identity_mapped)
 1:
 	movq	%rax, %cr4
 
-	jmp 1f
-1:
-
 	/* Flush the TLB (needed?) */
 	movq	%r9, %cr3