raw/ifpga: fix ARM build with clang

raw/ifpga: fix ARM build with clang

The patch fixes the compile issue with clang on ARM64, as well as
clang + X86 builing hosts.

Newly introduced #pragma pack(1) in the header file caused compiling
issues for the files who included it.

In file included from drivers/raw/ifpga_rawdev/base/ifpga_fme_dperf.c:5:
In file included from drivers/raw/ifpga_rawdev/base/ifpga_feature_dev.h:8:
drivers/raw/ifpga_rawdev/base/ifpga_hw.h:8:10: error:
the current #pragma pack alignment value is modified in the included file

The fix is to change the #pragma pack alignment locally and not have
effect on other files who included this header file.

Fixes: 56bb54ea1bdf ("raw/ifpga/base: add Intel FPGA OPAE share code")
Signed-off-by: Gavin Hu <gavin.hu@arm.com>
Reviewed-by: Honnappa Nagarahalli <honnappa.nagarahalli@arm.com>
Reviewed-by: Jerin Jacob <jerin.jacob@caviumnetworks.com>