objtool: Add missing endian conversion to read_annotate()

Trying to compile an x86 kernel on big endian results in this error:

net/ipv4/netfilter/iptable_nat.o: warning: objtool: iptable_nat_table_init+0x150: Unknown annotation type: 50331648
make[5]: *** [scripts/Makefile.build:287: net/ipv4/netfilter/iptable_nat.o] Error 255

Reason is a missing endian conversion in read_annotate().
Add the missing conversion to fix this.

Fixes: 2116b349 ("objtool: Generic annotation infrastructure")
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20250630131230.4130185-1-hca@linux.ibm.com