ShellPkg: Replace non-ASCII character in Pci.c to fix GCC build error

For Invalid character ‘-’ in Pci.c line 806 and line 811, using ASCII
encoding byte 0x2d to replace.

Example error from GCC 4.9:

ShellPkg/Library/UefiShellDebug1CommandsLib/Pci.c:806:5: error: converting to execution character set: Invalid or incomplete multibyte or wide character
     L"Ethernet (802.11a � 5 GHz)",
     ^

Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Qiu Shumin <shumin.qiu@intel.com>
Reviewed-by: Jaben Carsey <Jaben.carsey@intel.com>
Tested-by: Jordan Justen <jordan.l.justen@intel.com>

git-svn-id: https://svn.code.sf.net/p/edk2/code/trunk/edk2@15889 6f19259b-4bc3-4df7-8a09-765794883524