fixup for "arm64 entry: Add macro for reading symbol address from the trampoline"

__sdei_asm_trampoline_next_handler shouldn't have its own name as the
tramp_data_read_var takes the symbol name, and generates the name for
the value in the data page if CONFIG_RANDOMIZE_BASE is clear.

This means when CONFIG_RANDOMIZE_BASE is clear, this code won't compile
as __sdei_asm_trampoline_next_handler doesn't exist.

Use the proper name, and let the macro do its thing.

Reported-by: Florian Fainelli <f.fainelli@gmail.com>
Tested-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: James Morse <james.morse@arm.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>