EFM32 - change bitfield definitions to be unshifted.

[kbob]

Change all bitfield constant definitions for EFM32 to use unshifted values. Also fixed three errata in the definitions.

I also have an update for libopencm3-examples pull request #85 that uses the updated definitions. I will submit a pull request for that momentarily.

Rationale

In the comments on Pull Request #581, @karlp and @ChuckM asked that the bitfield definitions be unshifted. E.g., instead of

#define REG_FIELD_SHIFT 2
#define REG_FIELD_MASK 0xC0
#define REG_FIELD(x) (((x) << REG_FIELD_SHIFT) & REG_FIELD_MASK)
#define REG_FIELD_RED REG_FIELD(1)
#define REG_FIELD_BLUE REG_FIELD(2)

   REG = REG_FIELD_RED;

this is the preferred way.

#define REG_FIELD_RED 1
#define REG_FIELD_BLUE 2

    REG = REG_FIELD(REG_FIELD_RED);

[kbob]

The libopencm3-examples pull request is #116.

[ChuckM]

When you are #defining simply a number do you really need parenthesis around it?

[ChuckM]

other than the admittedly harmless extra parenthsis it looks good to me @kbob

[kbob]

I removed the parentheses.

[kbob]

This is superceded by #606.