rasdaemon: Add error decoding for MCA_CTL_SMU extended bits

[nchatrad]

Enable error decoding support for the newly added extended error bit descriptions from MCA_CTL_SMU.
b'0:11 can be decoded from existing array smca_smu2_mce_desc. Define a function to append the newly defined b'58:62 to the smca_smu2_mce_desc. This reduces the maintaining Reserved bits from b'12:57 in the code.

[mchehab]

for (i = 12, j = 0; i < smu2_bits || j < 5; i++, j++) {
for ( ; i < 58; i++)

It sounds a very bad idea to use a loop like that with magic numbers (12, 5, 58), as it makes:

• the table obfuscated, as one needs to read this init function to understand the value;
• error prone, as new patches for the table require checking such init code;
• less maintainable, as one needs to update not only the table but also this logic.

Instead, just let the compiler initialize "Reserved" at compile-time using designated initializers [1] like:

#define SMA_SMU2_MCE_SIZE 62

static const char * const smca_smu2_mce_desc[SMA_SMU2_MCE_SIZE] = {
       // Set a default value
	[0 ...SMA_SMU2_MCE_SIZE - 1] = "Reserved",
	// Initialize the fields that aren't reserved below here

[1] https://gcc.gnu.org/onlinedocs/gcc-3.3.1/gcc/Designated-Inits.html

[sathyapk]

Please track the changes in PR #167. This PR #144 can be closed.

[mchehab]

As requested, closing this, as PR#167 brings a new version.