x86/oprofile: introduce oprofile_add_data64()

The IBS implemention writes 64 bit register values to the cpu buffer
by writing two 32 values using oprofile_add_data(). This patch
introduces oprofile_add_data64() to write a single 64 bit value to the
buffer.

Signed-off-by: Robert Richter <robert.richter@amd.com>